float.c

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/*-------------------------------------------------------------------------
 *
 * float.c
 *    Functions for the built-in floating-point types.
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/float.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include <ctype.h>
#include <float.h>
#include <math.h>
#include <limits.h>
 
#include "catalog/pg_type.h"
#include "common/int.h"
#include "common/pg_prng.h"
#include "common/shortest_dec.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "utils/array.h"
#include "utils/float.h"
#include "utils/fmgrprotos.h"
#include "utils/sortsupport.h"
#include "utils/timestamp.h"
 
 
/*
 * Configurable GUC parameter
 *
 * If >0, use shortest-decimal format for output; this is both the default and
 * allows for compatibility with clients that explicitly set a value here to
 * get round-trip-accurate results. If 0 or less, then use the old, slow,
 * decimal rounding method.
 */
int         extra_float_digits = 1;
 
/* Cached constants for degree-based trig functions */
static bool degree_consts_set = false;
static float8 sin_30 = 0;
static float8 one_minus_cos_60 = 0;
static float8 asin_0_5 = 0;
static float8 acos_0_5 = 0;
static float8 atan_1_0 = 0;
static float8 tan_45 = 0;
static float8 cot_45 = 0;
 
/*
 * These are intentionally not static; don't "fix" them.  They will never
 * be referenced by other files, much less changed; but we don't want the
 * compiler to know that, else it might try to precompute expressions
 * involving them.  See comments for init_degree_constants().
 */
float8      degree_c_thirty = 30.0;
float8      degree_c_forty_five = 45.0;
float8      degree_c_sixty = 60.0;
float8      degree_c_one_half = 0.5;
float8      degree_c_one = 1.0;
 
/* State for drandom() and setseed() */
static bool drandom_seed_set = false;
static pg_prng_state drandom_seed;
 
/* Local function prototypes */
static double sind_q1(double x);
static double cosd_q1(double x);
static void init_degree_constants(void);
 
 
/*
 * We use these out-of-line ereport() calls to report float overflow,
 * underflow, and zero-divide, because following our usual practice of
 * repeating them at each call site would lead to a lot of code bloat.
 *
 * This does mean that you don't get a useful error location indicator.
 */
pg_noinline void
float_overflow_error(void)
{
    ereport(ERROR,
            (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
             errmsg("value out of range: overflow")));
}
 
pg_noinline void
float_underflow_error(void)
{
    ereport(ERROR,
            (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
             errmsg("value out of range: underflow")));
}
 
pg_noinline void
float_zero_divide_error(void)
{
    ereport(ERROR,
            (errcode(ERRCODE_DIVISION_BY_ZERO),
             errmsg("division by zero")));
}
 
 
/*
 * Returns -1 if 'val' represents negative infinity, 1 if 'val'
 * represents (positive) infinity, and 0 otherwise. On some platforms,
 * this is equivalent to the isinf() macro, but not everywhere: C99
 * does not specify that isinf() needs to distinguish between positive
 * and negative infinity.
 */
int
is_infinite(double val)
{
    int         inf = isinf(val);
 
    if (inf == 0)
        return 0;
    else if (val > 0)
        return 1;
    else
        return -1;
}
 
 
/* ========== USER I/O ROUTINES ========== */
 
 
/*
 *      float4in        - converts "num" to float4
 *
 * Note that this code now uses strtof(), where it used to use strtod().
 *
 * The motivation for using strtof() is to avoid a double-rounding problem:
 * for certain decimal inputs, if you round the input correctly to a double,
 * and then round the double to a float, the result is incorrect in that it
 * does not match the result of rounding the decimal value to float directly.
 *
 * One of the best examples is 7.038531e-26:
 *
 * 0xAE43FDp-107 = 7.03853069185120912085...e-26
 *      midpoint   7.03853100000000022281...e-26
 * 0xAE43FEp-107 = 7.03853130814879132477...e-26
 *
 * making 0xAE43FDp-107 the correct float result, but if you do the conversion
 * via a double, you get
 *
 * 0xAE43FD.7FFFFFF8p-107 = 7.03853099999999907487...e-26
 *               midpoint   7.03853099999999964884...e-26
 * 0xAE43FD.80000000p-107 = 7.03853100000000022281...e-26
 * 0xAE43FD.80000008p-107 = 7.03853100000000137076...e-26
 *
 * so the value rounds to the double exactly on the midpoint between the two
 * nearest floats, and then rounding again to a float gives the incorrect
 * result of 0xAE43FEp-107.
 *
 */
Datum
float4in(PG_FUNCTION_ARGS)
{
    char       *num = PG_GETARG_CSTRING(0);
 
    PG_RETURN_FLOAT4(float4in_internal(num, NULL, "real", num,
                                       fcinfo->context));
}
 
/*
 * float4in_internal - guts of float4in()
 *
 * This is exposed for use by functions that want a reasonably
 * platform-independent way of inputting floats. The behavior is
 * essentially like strtof + ereturn on error.
 *
 * Uses the same API as float8in_internal below, so most of its
 * comments also apply here, except regarding use in geometric types.
 */
float4
float4in_internal(char *num, char **endptr_p,
                  const char *type_name, const char *orig_string,
                  struct Node *escontext)
{
    float       val;
    char       *endptr;
 
    /*
     * endptr points to the first character _after_ the sequence we recognized
     * as a valid floating point number. orig_string points to the original
     * input string.
     */
 
    /* skip leading whitespace */
    while (*num != '\0' && isspace((unsigned char) *num))
        num++;
 
    /*
     * Check for an empty-string input to begin with, to avoid the vagaries of
     * strtod() on different platforms.
     */
    if (*num == '\0')
        ereturn(escontext, 0,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type %s: \"%s\"",
                        type_name, orig_string)));
 
    errno = 0;
    val = strtof(num, &endptr);
 
    /* did we not see anything that looks like a double? */
    if (endptr == num || errno != 0)
    {
        int         save_errno = errno;
 
        /*
         * C99 requires that strtof() accept NaN, [+-]Infinity, and [+-]Inf,
         * but not all platforms support all of these (and some accept them
         * but set ERANGE anyway...)  Therefore, we check for these inputs
         * ourselves if strtof() fails.
         *
         * Note: C99 also requires hexadecimal input as well as some extended
         * forms of NaN, but we consider these forms unportable and don't try
         * to support them.  You can use 'em if your strtof() takes 'em.
         */
        if (pg_strncasecmp(num, "NaN", 3) == 0)
        {
            val = get_float4_nan();
            endptr = num + 3;
        }
        else if (pg_strncasecmp(num, "Infinity", 8) == 0)
        {
            val = get_float4_infinity();
            endptr = num + 8;
        }
        else if (pg_strncasecmp(num, "+Infinity", 9) == 0)
        {
            val = get_float4_infinity();
            endptr = num + 9;
        }
        else if (pg_strncasecmp(num, "-Infinity", 9) == 0)
        {
            val = -get_float4_infinity();
            endptr = num + 9;
        }
        else if (pg_strncasecmp(num, "inf", 3) == 0)
        {
            val = get_float4_infinity();
            endptr = num + 3;
        }
        else if (pg_strncasecmp(num, "+inf", 4) == 0)
        {
            val = get_float4_infinity();
            endptr = num + 4;
        }
        else if (pg_strncasecmp(num, "-inf", 4) == 0)
        {
            val = -get_float4_infinity();
            endptr = num + 4;
        }
        else if (save_errno == ERANGE)
        {
            /*
             * Some platforms return ERANGE for denormalized numbers (those
             * that are not zero, but are too close to zero to have full
             * precision).  We'd prefer not to throw error for that, so try to
             * detect whether it's a "real" out-of-range condition by checking
             * to see if the result is zero or huge.
             */
            if (val == 0.0 ||
#if !defined(HUGE_VALF)
                isinf(val)
#else
                (val >= HUGE_VALF || val <= -HUGE_VALF)
#endif
                )
            {
                /* see comments in float8in_internal for rationale */
                char       *errnumber = pstrdup(num);
 
                errnumber[endptr - num] = '\0';
 
                ereturn(escontext, 0,
                        (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                         errmsg("\"%s\" is out of range for type real",
                                errnumber)));
            }
        }
        else
            ereturn(escontext, 0,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("invalid input syntax for type %s: \"%s\"",
                            type_name, orig_string)));
    }
 
    /* skip trailing whitespace */
    while (*endptr != '\0' && isspace((unsigned char) *endptr))
        endptr++;
 
    /* report stopping point if wanted, else complain if not end of string */
    if (endptr_p)
        *endptr_p = endptr;
    else if (*endptr != '\0')
        ereturn(escontext, 0,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type %s: \"%s\"",
                        type_name, orig_string)));
 
    return val;
}
 
/*
 *      float4out       - converts a float4 number to a string
 *                        using a standard output format
 */
Datum
float4out(PG_FUNCTION_ARGS)
{
    float4      num = PG_GETARG_FLOAT4(0);
    char       *ascii = (char *) palloc(32);
    int         ndig = FLT_DIG + extra_float_digits;
 
    if (extra_float_digits > 0)
    {
        float_to_shortest_decimal_buf(num, ascii);
        PG_RETURN_CSTRING(ascii);
    }
 
    (void) pg_strfromd(ascii, 32, ndig, num);
    PG_RETURN_CSTRING(ascii);
}
 
/*
 *      float4recv          - converts external binary format to float4
 */
Datum
float4recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
 
    PG_RETURN_FLOAT4(pq_getmsgfloat4(buf));
}
 
/*
 *      float4send          - converts float4 to binary format
 */
Datum
float4send(PG_FUNCTION_ARGS)
{
    float4      num = PG_GETARG_FLOAT4(0);
    StringInfoData buf;
 
    pq_begintypsend(&buf);
    pq_sendfloat4(&buf, num);
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
 
/*
 *      float8in        - converts "num" to float8
 */
Datum
float8in(PG_FUNCTION_ARGS)
{
    char       *num = PG_GETARG_CSTRING(0);
 
    PG_RETURN_FLOAT8(float8in_internal(num, NULL, "double precision", num,
                                       fcinfo->context));
}
 
/*
 * float8in_internal - guts of float8in()
 *
 * This is exposed for use by functions that want a reasonably
 * platform-independent way of inputting doubles.  The behavior is
 * essentially like strtod + ereturn on error, but note the following
 * differences:
 * 1. Both leading and trailing whitespace are skipped.
 * 2. If endptr_p is NULL, we report error if there's trailing junk.
 * Otherwise, it's up to the caller to complain about trailing junk.
 * 3. In event of a syntax error, the report mentions the given type_name
 * and prints orig_string as the input; this is meant to support use of
 * this function with types such as "box" and "point", where what we are
 * parsing here is just a substring of orig_string.
 *
 * If escontext points to an ErrorSaveContext node, that is filled instead
 * of throwing an error; the caller must check SOFT_ERROR_OCCURRED()
 * to detect errors.
 *
 * "num" could validly be declared "const char *", but that results in an
 * unreasonable amount of extra casting both here and in callers, so we don't.
 */
float8
float8in_internal(char *num, char **endptr_p,
                  const char *type_name, const char *orig_string,
                  struct Node *escontext)
{
    double      val;
    char       *endptr;
 
    /* skip leading whitespace */
    while (*num != '\0' && isspace((unsigned char) *num))
        num++;
 
    /*
     * Check for an empty-string input to begin with, to avoid the vagaries of
     * strtod() on different platforms.
     */
    if (*num == '\0')
        ereturn(escontext, 0,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type %s: \"%s\"",
                        type_name, orig_string)));
 
    errno = 0;
    val = strtod(num, &endptr);
 
    /* did we not see anything that looks like a double? */
    if (endptr == num || errno != 0)
    {
        int         save_errno = errno;
 
        /*
         * C99 requires that strtod() accept NaN, [+-]Infinity, and [+-]Inf,
         * but not all platforms support all of these (and some accept them
         * but set ERANGE anyway...)  Therefore, we check for these inputs
         * ourselves if strtod() fails.
         *
         * Note: C99 also requires hexadecimal input as well as some extended
         * forms of NaN, but we consider these forms unportable and don't try
         * to support them.  You can use 'em if your strtod() takes 'em.
         */
        if (pg_strncasecmp(num, "NaN", 3) == 0)
        {
            val = get_float8_nan();
            endptr = num + 3;
        }
        else if (pg_strncasecmp(num, "Infinity", 8) == 0)
        {
            val = get_float8_infinity();
            endptr = num + 8;
        }
        else if (pg_strncasecmp(num, "+Infinity", 9) == 0)
        {
            val = get_float8_infinity();
            endptr = num + 9;
        }
        else if (pg_strncasecmp(num, "-Infinity", 9) == 0)
        {
            val = -get_float8_infinity();
            endptr = num + 9;
        }
        else if (pg_strncasecmp(num, "inf", 3) == 0)
        {
            val = get_float8_infinity();
            endptr = num + 3;
        }
        else if (pg_strncasecmp(num, "+inf", 4) == 0)
        {
            val = get_float8_infinity();
            endptr = num + 4;
        }
        else if (pg_strncasecmp(num, "-inf", 4) == 0)
        {
            val = -get_float8_infinity();
            endptr = num + 4;
        }
        else if (save_errno == ERANGE)
        {
            /*
             * Some platforms return ERANGE for denormalized numbers (those
             * that are not zero, but are too close to zero to have full
             * precision).  We'd prefer not to throw error for that, so try to
             * detect whether it's a "real" out-of-range condition by checking
             * to see if the result is zero or huge.
             *
             * On error, we intentionally complain about double precision not
             * the given type name, and we print only the part of the string
             * that is the current number.
             */
            if (val == 0.0 || val >= HUGE_VAL || val <= -HUGE_VAL)
            {
                char       *errnumber = pstrdup(num);
 
                errnumber[endptr - num] = '\0';
                ereturn(escontext, 0,
                        (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                         errmsg("\"%s\" is out of range for type double precision",
                                errnumber)));
            }
        }
        else
            ereturn(escontext, 0,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("invalid input syntax for type %s: \"%s\"",
                            type_name, orig_string)));
    }
 
    /* skip trailing whitespace */
    while (*endptr != '\0' && isspace((unsigned char) *endptr))
        endptr++;
 
    /* report stopping point if wanted, else complain if not end of string */
    if (endptr_p)
        *endptr_p = endptr;
    else if (*endptr != '\0')
        ereturn(escontext, 0,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type %s: \"%s\"",
                        type_name, orig_string)));
 
    return val;
}
 
 
/*
 *      float8out       - converts float8 number to a string
 *                        using a standard output format
 */
Datum
float8out(PG_FUNCTION_ARGS)
{
    float8      num = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_CSTRING(float8out_internal(num));
}
 
/*
 * float8out_internal - guts of float8out()
 *
 * This is exposed for use by functions that want a reasonably
 * platform-independent way of outputting doubles.
 * The result is always palloc'd.
 */
char *
float8out_internal(double num)
{
    char       *ascii = (char *) palloc(32);
    int         ndig = DBL_DIG + extra_float_digits;
 
    if (extra_float_digits > 0)
    {
        double_to_shortest_decimal_buf(num, ascii);
        return ascii;
    }
 
    (void) pg_strfromd(ascii, 32, ndig, num);
    return ascii;
}
 
/*
 *      float8recv          - converts external binary format to float8
 */
Datum
float8recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
 
    PG_RETURN_FLOAT8(pq_getmsgfloat8(buf));
}
 
/*
 *      float8send          - converts float8 to binary format
 */
Datum
float8send(PG_FUNCTION_ARGS)
{
    float8      num = PG_GETARG_FLOAT8(0);
    StringInfoData buf;
 
    pq_begintypsend(&buf);
    pq_sendfloat8(&buf, num);
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
 
 
/* ========== PUBLIC ROUTINES ========== */
 
 
/*
 *      ======================
 *      FLOAT4 BASE OPERATIONS
 *      ======================
 */
 
/*
 *      float4abs       - returns |arg1| (absolute value)
 */
Datum
float4abs(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
 
    PG_RETURN_FLOAT4(fabsf(arg1));
}
 
/*
 *      float4um        - returns -arg1 (unary minus)
 */
Datum
float4um(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      result;
 
    result = -arg1;
    PG_RETURN_FLOAT4(result);
}
 
Datum
float4up(PG_FUNCTION_ARGS)
{
    float4      arg = PG_GETARG_FLOAT4(0);
 
    PG_RETURN_FLOAT4(arg);
}
 
Datum
float4larger(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
    float4      result;
 
    if (float4_gt(arg1, arg2))
        result = arg1;
    else
        result = arg2;
    PG_RETURN_FLOAT4(result);
}
 
Datum
float4smaller(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
    float4      result;
 
    if (float4_lt(arg1, arg2))
        result = arg1;
    else
        result = arg2;
    PG_RETURN_FLOAT4(result);
}
 
/*
 *      ======================
 *      FLOAT8 BASE OPERATIONS
 *      ======================
 */
 
/*
 *      float8abs       - returns |arg1| (absolute value)
 */
Datum
float8abs(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(fabs(arg1));
}
 
 
/*
 *      float8um        - returns -arg1 (unary minus)
 */
Datum
float8um(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    result = -arg1;
    PG_RETURN_FLOAT8(result);
}
 
Datum
float8up(PG_FUNCTION_ARGS)
{
    float8      arg = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(arg);
}
 
Datum
float8larger(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
    float8      result;
 
    if (float8_gt(arg1, arg2))
        result = arg1;
    else
        result = arg2;
    PG_RETURN_FLOAT8(result);
}
 
Datum
float8smaller(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
    float8      result;
 
    if (float8_lt(arg1, arg2))
        result = arg1;
    else
        result = arg2;
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      ====================
 *      ARITHMETIC OPERATORS
 *      ====================
 */
 
/*
 *      float4pl        - returns arg1 + arg2
 *      float4mi        - returns arg1 - arg2
 *      float4mul       - returns arg1 * arg2
 *      float4div       - returns arg1 / arg2
 */
Datum
float4pl(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT4(float4_pl(arg1, arg2));
}
 
Datum
float4mi(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT4(float4_mi(arg1, arg2));
}
 
Datum
float4mul(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT4(float4_mul(arg1, arg2));
}
 
Datum
float4div(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT4(float4_div(arg1, arg2));
}
 
/*
 *      float8pl        - returns arg1 + arg2
 *      float8mi        - returns arg1 - arg2
 *      float8mul       - returns arg1 * arg2
 *      float8div       - returns arg1 / arg2
 */
Datum
float8pl(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_pl(arg1, arg2));
}
 
Datum
float8mi(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_mi(arg1, arg2));
}
 
Datum
float8mul(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_mul(arg1, arg2));
}
 
Datum
float8div(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_div(arg1, arg2));
}
 
 
/*
 *      ====================
 *      COMPARISON OPERATORS
 *      ====================
 */
 
/*
 *      float4{eq,ne,lt,le,gt,ge}       - float4/float4 comparison operations
 */
int
float4_cmp_internal(float4 a, float4 b)
{
    if (float4_gt(a, b))
        return 1;
    if (float4_lt(a, b))
        return -1;
    return 0;
}
 
Datum
float4eq(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float4_eq(arg1, arg2));
}
 
Datum
float4ne(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float4_ne(arg1, arg2));
}
 
Datum
float4lt(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float4_lt(arg1, arg2));
}
 
Datum
float4le(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float4_le(arg1, arg2));
}
 
Datum
float4gt(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float4_gt(arg1, arg2));
}
 
Datum
float4ge(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float4_ge(arg1, arg2));
}
 
Datum
btfloat4cmp(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_INT32(float4_cmp_internal(arg1, arg2));
}
 
static int
btfloat4fastcmp(Datum x, Datum y, SortSupport ssup)
{
    float4      arg1 = DatumGetFloat4(x);
    float4      arg2 = DatumGetFloat4(y);
 
    return float4_cmp_internal(arg1, arg2);
}
 
Datum
btfloat4sortsupport(PG_FUNCTION_ARGS)
{
    SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
 
    ssup->comparator = btfloat4fastcmp;
    PG_RETURN_VOID();
}
 
/*
 *      float8{eq,ne,lt,le,gt,ge}       - float8/float8 comparison operations
 */
int
float8_cmp_internal(float8 a, float8 b)
{
    if (float8_gt(a, b))
        return 1;
    if (float8_lt(a, b))
        return -1;
    return 0;
}
 
Datum
float8eq(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_eq(arg1, arg2));
}
 
Datum
float8ne(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_ne(arg1, arg2));
}
 
Datum
float8lt(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_lt(arg1, arg2));
}
 
Datum
float8le(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_le(arg1, arg2));
}
 
Datum
float8gt(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_gt(arg1, arg2));
}
 
Datum
float8ge(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_ge(arg1, arg2));
}
 
Datum
btfloat8cmp(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_INT32(float8_cmp_internal(arg1, arg2));
}
 
static int
btfloat8fastcmp(Datum x, Datum y, SortSupport ssup)
{
    float8      arg1 = DatumGetFloat8(x);
    float8      arg2 = DatumGetFloat8(y);
 
    return float8_cmp_internal(arg1, arg2);
}
 
Datum
btfloat8sortsupport(PG_FUNCTION_ARGS)
{
    SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
 
    ssup->comparator = btfloat8fastcmp;
    PG_RETURN_VOID();
}
 
Datum
btfloat48cmp(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    /* widen float4 to float8 and then compare */
    PG_RETURN_INT32(float8_cmp_internal(arg1, arg2));
}
 
Datum
btfloat84cmp(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    /* widen float4 to float8 and then compare */
    PG_RETURN_INT32(float8_cmp_internal(arg1, arg2));
}
 
/*
 * in_range support function for float8.
 *
 * Note: we needn't supply a float8_float4 variant, as implicit coercion
 * of the offset value takes care of that scenario just as well.
 */
Datum
in_range_float8_float8(PG_FUNCTION_ARGS)
{
    float8      val = PG_GETARG_FLOAT8(0);
    float8      base = PG_GETARG_FLOAT8(1);
    float8      offset = PG_GETARG_FLOAT8(2);
    bool        sub = PG_GETARG_BOOL(3);
    bool        less = PG_GETARG_BOOL(4);
    float8      sum;
 
    /*
     * Reject negative or NaN offset.  Negative is per spec, and NaN is
     * because appropriate semantics for that seem non-obvious.
     */
    if (isnan(offset) || offset < 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PRECEDING_OR_FOLLOWING_SIZE),
                 errmsg("invalid preceding or following size in window function")));
 
    /*
     * Deal with cases where val and/or base is NaN, following the rule that
     * NaN sorts after non-NaN (cf float8_cmp_internal).  The offset cannot
     * affect the conclusion.
     */
    if (isnan(val))
    {
        if (isnan(base))
            PG_RETURN_BOOL(true);   /* NAN = NAN */
        else
            PG_RETURN_BOOL(!less);  /* NAN > non-NAN */
    }
    else if (isnan(base))
    {
        PG_RETURN_BOOL(less);   /* non-NAN < NAN */
    }
 
    /*
     * Deal with cases where both base and offset are infinite, and computing
     * base +/- offset would produce NaN.  This corresponds to a window frame
     * whose boundary infinitely precedes +inf or infinitely follows -inf,
     * which is not well-defined.  For consistency with other cases involving
     * infinities, such as the fact that +inf infinitely follows +inf, we
     * choose to assume that +inf infinitely precedes +inf and -inf infinitely
     * follows -inf, and therefore that all finite and infinite values are in
     * such a window frame.
     *
     * offset is known positive, so we need only check the sign of base in
     * this test.
     */
    if (isinf(offset) && isinf(base) &&
        (sub ? base > 0 : base < 0))
        PG_RETURN_BOOL(true);
 
    /*
     * Otherwise it should be safe to compute base +/- offset.  We trust the
     * FPU to cope if an input is +/-inf or the true sum would overflow, and
     * produce a suitably signed infinity, which will compare properly against
     * val whether or not that's infinity.
     */
    if (sub)
        sum = base - offset;
    else
        sum = base + offset;
 
    if (less)
        PG_RETURN_BOOL(val <= sum);
    else
        PG_RETURN_BOOL(val >= sum);
}
 
/*
 * in_range support function for float4.
 *
 * We would need a float4_float8 variant in any case, so we supply that and
 * let implicit coercion take care of the float4_float4 case.
 */
Datum
in_range_float4_float8(PG_FUNCTION_ARGS)
{
    float4      val = PG_GETARG_FLOAT4(0);
    float4      base = PG_GETARG_FLOAT4(1);
    float8      offset = PG_GETARG_FLOAT8(2);
    bool        sub = PG_GETARG_BOOL(3);
    bool        less = PG_GETARG_BOOL(4);
    float8      sum;
 
    /*
     * Reject negative or NaN offset.  Negative is per spec, and NaN is
     * because appropriate semantics for that seem non-obvious.
     */
    if (isnan(offset) || offset < 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PRECEDING_OR_FOLLOWING_SIZE),
                 errmsg("invalid preceding or following size in window function")));
 
    /*
     * Deal with cases where val and/or base is NaN, following the rule that
     * NaN sorts after non-NaN (cf float8_cmp_internal).  The offset cannot
     * affect the conclusion.
     */
    if (isnan(val))
    {
        if (isnan(base))
            PG_RETURN_BOOL(true);   /* NAN = NAN */
        else
            PG_RETURN_BOOL(!less);  /* NAN > non-NAN */
    }
    else if (isnan(base))
    {
        PG_RETURN_BOOL(less);   /* non-NAN < NAN */
    }
 
    /*
     * Deal with cases where both base and offset are infinite, and computing
     * base +/- offset would produce NaN.  This corresponds to a window frame
     * whose boundary infinitely precedes +inf or infinitely follows -inf,
     * which is not well-defined.  For consistency with other cases involving
     * infinities, such as the fact that +inf infinitely follows +inf, we
     * choose to assume that +inf infinitely precedes +inf and -inf infinitely
     * follows -inf, and therefore that all finite and infinite values are in
     * such a window frame.
     *
     * offset is known positive, so we need only check the sign of base in
     * this test.
     */
    if (isinf(offset) && isinf(base) &&
        (sub ? base > 0 : base < 0))
        PG_RETURN_BOOL(true);
 
    /*
     * Otherwise it should be safe to compute base +/- offset.  We trust the
     * FPU to cope if an input is +/-inf or the true sum would overflow, and
     * produce a suitably signed infinity, which will compare properly against
     * val whether or not that's infinity.
     */
    if (sub)
        sum = base - offset;
    else
        sum = base + offset;
 
    if (less)
        PG_RETURN_BOOL(val <= sum);
    else
        PG_RETURN_BOOL(val >= sum);
}
 
 
/*
 *      ===================
 *      CONVERSION ROUTINES
 *      ===================
 */
 
/*
 *      ftod            - converts a float4 number to a float8 number
 */
Datum
ftod(PG_FUNCTION_ARGS)
{
    float4      num = PG_GETARG_FLOAT4(0);
 
    PG_RETURN_FLOAT8((float8) num);
}
 
 
/*
 *      dtof            - converts a float8 number to a float4 number
 */
Datum
dtof(PG_FUNCTION_ARGS)
{
    float8      num = PG_GETARG_FLOAT8(0);
    float4      result;
 
    result = (float4) num;
    if (unlikely(isinf(result)) && !isinf(num))
        float_overflow_error();
    if (unlikely(result == 0.0f) && num != 0.0)
        float_underflow_error();
 
    PG_RETURN_FLOAT4(result);
}
 
 
/*
 *      dtoi4           - converts a float8 number to an int4 number
 */
Datum
dtoi4(PG_FUNCTION_ARGS)
{
    float8      num = PG_GETARG_FLOAT8(0);
 
    /*
     * Get rid of any fractional part in the input.  This is so we don't fail
     * on just-out-of-range values that would round into range.  Note
     * assumption that rint() will pass through a NaN or Inf unchanged.
     */
    num = rint(num);
 
    /* Range check */
    if (unlikely(isnan(num) || !FLOAT8_FITS_IN_INT32(num)))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("integer out of range")));
 
    PG_RETURN_INT32((int32) num);
}
 
 
/*
 *      dtoi2           - converts a float8 number to an int2 number
 */
Datum
dtoi2(PG_FUNCTION_ARGS)
{
    float8      num = PG_GETARG_FLOAT8(0);
 
    /*
     * Get rid of any fractional part in the input.  This is so we don't fail
     * on just-out-of-range values that would round into range.  Note
     * assumption that rint() will pass through a NaN or Inf unchanged.
     */
    num = rint(num);
 
    /* Range check */
    if (unlikely(isnan(num) || !FLOAT8_FITS_IN_INT16(num)))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("smallint out of range")));
 
    PG_RETURN_INT16((int16) num);
}
 
 
/*
 *      i4tod           - converts an int4 number to a float8 number
 */
Datum
i4tod(PG_FUNCTION_ARGS)
{
    int32       num = PG_GETARG_INT32(0);
 
    PG_RETURN_FLOAT8((float8) num);
}
 
 
/*
 *      i2tod           - converts an int2 number to a float8 number
 */
Datum
i2tod(PG_FUNCTION_ARGS)
{
    int16       num = PG_GETARG_INT16(0);
 
    PG_RETURN_FLOAT8((float8) num);
}
 
 
/*
 *      ftoi4           - converts a float4 number to an int4 number
 */
Datum
ftoi4(PG_FUNCTION_ARGS)
{
    float4      num = PG_GETARG_FLOAT4(0);
 
    /*
     * Get rid of any fractional part in the input.  This is so we don't fail
     * on just-out-of-range values that would round into range.  Note
     * assumption that rint() will pass through a NaN or Inf unchanged.
     */
    num = rint(num);
 
    /* Range check */
    if (unlikely(isnan(num) || !FLOAT4_FITS_IN_INT32(num)))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("integer out of range")));
 
    PG_RETURN_INT32((int32) num);
}
 
 
/*
 *      ftoi2           - converts a float4 number to an int2 number
 */
Datum
ftoi2(PG_FUNCTION_ARGS)
{
    float4      num = PG_GETARG_FLOAT4(0);
 
    /*
     * Get rid of any fractional part in the input.  This is so we don't fail
     * on just-out-of-range values that would round into range.  Note
     * assumption that rint() will pass through a NaN or Inf unchanged.
     */
    num = rint(num);
 
    /* Range check */
    if (unlikely(isnan(num) || !FLOAT4_FITS_IN_INT16(num)))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("smallint out of range")));
 
    PG_RETURN_INT16((int16) num);
}
 
 
/*
 *      i4tof           - converts an int4 number to a float4 number
 */
Datum
i4tof(PG_FUNCTION_ARGS)
{
    int32       num = PG_GETARG_INT32(0);
 
    PG_RETURN_FLOAT4((float4) num);
}
 
 
/*
 *      i2tof           - converts an int2 number to a float4 number
 */
Datum
i2tof(PG_FUNCTION_ARGS)
{
    int16       num = PG_GETARG_INT16(0);
 
    PG_RETURN_FLOAT4((float4) num);
}
 
 
/*
 *      =======================
 *      RANDOM FLOAT8 OPERATORS
 *      =======================
 */
 
/*
 *      dround          - returns   ROUND(arg1)
 */
Datum
dround(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(rint(arg1));
}
 
/*
 *      dceil           - returns the smallest integer greater than or
 *                        equal to the specified float
 */
Datum
dceil(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(ceil(arg1));
}
 
/*
 *      dfloor          - returns the largest integer lesser than or
 *                        equal to the specified float
 */
Datum
dfloor(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(floor(arg1));
}
 
/*
 *      dsign           - returns -1 if the argument is less than 0, 0
 *                        if the argument is equal to 0, and 1 if the
 *                        argument is greater than zero.
 */
Datum
dsign(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    if (arg1 > 0)
        result = 1.0;
    else if (arg1 < 0)
        result = -1.0;
    else
        result = 0.0;
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      dtrunc          - returns truncation-towards-zero of arg1,
 *                        arg1 >= 0 ... the greatest integer less
 *                                      than or equal to arg1
 *                        arg1 < 0  ... the least integer greater
 *                                      than or equal to arg1
 */
Datum
dtrunc(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    if (arg1 >= 0)
        result = floor(arg1);
    else
        result = -floor(-arg1);
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dsqrt           - returns square root of arg1
 */
Datum
dsqrt(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    if (arg1 < 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
                 errmsg("cannot take square root of a negative number")));
 
    result = sqrt(arg1);
    if (unlikely(isinf(result)) && !isinf(arg1))
        float_overflow_error();
    if (unlikely(result == 0.0) && arg1 != 0.0)
        float_underflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dcbrt           - returns cube root of arg1
 */
Datum
dcbrt(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    result = cbrt(arg1);
    if (unlikely(isinf(result)) && !isinf(arg1))
        float_overflow_error();
    if (unlikely(result == 0.0) && arg1 != 0.0)
        float_underflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dpow            - returns pow(arg1,arg2)
 */
Datum
dpow(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
    float8      result;
 
    /*
     * The POSIX spec says that NaN ^ 0 = 1, and 1 ^ NaN = 1, while all other
     * cases with NaN inputs yield NaN (with no error).  Many older platforms
     * get one or more of these cases wrong, so deal with them via explicit
     * logic rather than trusting pow(3).
     */
    if (isnan(arg1))
    {
        if (isnan(arg2) || arg2 != 0.0)
            PG_RETURN_FLOAT8(get_float8_nan());
        PG_RETURN_FLOAT8(1.0);
    }
    if (isnan(arg2))
    {
        if (arg1 != 1.0)
            PG_RETURN_FLOAT8(get_float8_nan());
        PG_RETURN_FLOAT8(1.0);
    }
 
    /*
     * The SQL spec requires that we emit a particular SQLSTATE error code for
     * certain error conditions.  Specifically, we don't return a
     * divide-by-zero error code for 0 ^ -1.
     */
    if (arg1 == 0 && arg2 < 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
                 errmsg("zero raised to a negative power is undefined")));
    if (arg1 < 0 && floor(arg2) != arg2)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
                 errmsg("a negative number raised to a non-integer power yields a complex result")));
 
    /*
     * We don't trust the platform's pow() to handle infinity cases per POSIX
     * spec either, so deal with those explicitly too.  It's easier to handle
     * infinite y first, so that it doesn't matter if x is also infinite.
     */
    if (isinf(arg2))
    {
        float8      absx = fabs(arg1);
 
        if (absx == 1.0)
            result = 1.0;
        else if (arg2 > 0.0)    /* y = +Inf */
        {
            if (absx > 1.0)
                result = arg2;
            else
                result = 0.0;
        }
        else                    /* y = -Inf */
        {
            if (absx > 1.0)
                result = 0.0;
            else
                result = -arg2;
        }
    }
    else if (isinf(arg1))
    {
        if (arg2 == 0.0)
            result = 1.0;
        else if (arg1 > 0.0)    /* x = +Inf */
        {
            if (arg2 > 0.0)
                result = arg1;
            else
                result = 0.0;
        }
        else                    /* x = -Inf */
        {
            /*
             * Per POSIX, the sign of the result depends on whether y is an
             * odd integer.  Since x < 0, we already know from the previous
             * domain check that y is an integer.  It is odd if y/2 is not
             * also an integer.
             */
            float8      halfy = arg2 / 2;   /* should be computed exactly */
            bool        yisoddinteger = (floor(halfy) != halfy);
 
            if (arg2 > 0.0)
                result = yisoddinteger ? arg1 : -arg1;
            else
                result = yisoddinteger ? -0.0 : 0.0;
        }
    }
    else
    {
        /*
         * pow() sets errno on only some platforms, depending on whether it
         * follows _IEEE_, _POSIX_, _XOPEN_, or _SVID_, so we must check both
         * errno and invalid output values.  (We can't rely on just the
         * latter, either; some old platforms return a large-but-finite
         * HUGE_VAL when reporting overflow.)
         */
        errno = 0;
        result = pow(arg1, arg2);
        if (errno == EDOM || isnan(result))
        {
            /*
             * We handled all possible domain errors above, so this should be
             * impossible.  However, old glibc versions on x86 have a bug that
             * causes them to fail this way for abs(y) greater than 2^63:
             *
             * https://sourceware.org/bugzilla/show_bug.cgi?id=3866
             *
             * Hence, if we get here, assume y is finite but large (large
             * enough to be certainly even). The result should be 0 if x == 0,
             * 1.0 if abs(x) == 1.0, otherwise an overflow or underflow error.
             */
            if (arg1 == 0.0)
                result = 0.0;   /* we already verified y is positive */
            else
            {
                float8      absx = fabs(arg1);
 
                if (absx == 1.0)
                    result = 1.0;
                else if (arg2 >= 0.0 ? (absx > 1.0) : (absx < 1.0))
                    float_overflow_error();
                else
                    float_underflow_error();
            }
        }
        else if (errno == ERANGE)
        {
            if (result != 0.0)
                float_overflow_error();
            else
                float_underflow_error();
        }
        else
        {
            if (unlikely(isinf(result)))
                float_overflow_error();
            if (unlikely(result == 0.0) && arg1 != 0.0)
                float_underflow_error();
        }
    }
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dexp            - returns the exponential function of arg1
 */
Datum
dexp(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * Handle NaN and Inf cases explicitly.  This avoids needing to assume
     * that the platform's exp() conforms to POSIX for these cases, and it
     * removes some edge cases for the overflow checks below.
     */
    if (isnan(arg1))
        result = arg1;
    else if (isinf(arg1))
    {
        /* Per POSIX, exp(-Inf) is 0 */
        result = (arg1 > 0.0) ? arg1 : 0;
    }
    else
    {
        /*
         * On some platforms, exp() will not set errno but just return Inf or
         * zero to report overflow/underflow; therefore, test both cases.
         */
        errno = 0;
        result = exp(arg1);
        if (unlikely(errno == ERANGE))
        {
            if (result != 0.0)
                float_overflow_error();
            else
                float_underflow_error();
        }
        else if (unlikely(isinf(result)))
            float_overflow_error();
        else if (unlikely(result == 0.0))
            float_underflow_error();
    }
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dlog1           - returns the natural logarithm of arg1
 */
Datum
dlog1(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * Emit particular SQLSTATE error codes for ln(). This is required by the
     * SQL standard.
     */
    if (arg1 == 0.0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_LOG),
                 errmsg("cannot take logarithm of zero")));
    if (arg1 < 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_LOG),
                 errmsg("cannot take logarithm of a negative number")));
 
    result = log(arg1);
    if (unlikely(isinf(result)) && !isinf(arg1))
        float_overflow_error();
    if (unlikely(result == 0.0) && arg1 != 1.0)
        float_underflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dlog10          - returns the base 10 logarithm of arg1
 */
Datum
dlog10(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * Emit particular SQLSTATE error codes for log(). The SQL spec doesn't
     * define log(), but it does define ln(), so it makes sense to emit the
     * same error code for an analogous error condition.
     */
    if (arg1 == 0.0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_LOG),
                 errmsg("cannot take logarithm of zero")));
    if (arg1 < 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_LOG),
                 errmsg("cannot take logarithm of a negative number")));
 
    result = log10(arg1);
    if (unlikely(isinf(result)) && !isinf(arg1))
        float_overflow_error();
    if (unlikely(result == 0.0) && arg1 != 1.0)
        float_underflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dacos           - returns the arccos of arg1 (radians)
 */
Datum
dacos(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /*
     * The principal branch of the inverse cosine function maps values in the
     * range [-1, 1] to values in the range [0, Pi], so we should reject any
     * inputs outside that range and the result will always be finite.
     */
    if (arg1 < -1.0 || arg1 > 1.0)
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    result = acos(arg1);
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dasin           - returns the arcsin of arg1 (radians)
 */
Datum
dasin(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /*
     * The principal branch of the inverse sine function maps values in the
     * range [-1, 1] to values in the range [-Pi/2, Pi/2], so we should reject
     * any inputs outside that range and the result will always be finite.
     */
    if (arg1 < -1.0 || arg1 > 1.0)
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    result = asin(arg1);
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      datan           - returns the arctan of arg1 (radians)
 */
Datum
datan(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /*
     * The principal branch of the inverse tangent function maps all inputs to
     * values in the range [-Pi/2, Pi/2], so the result should always be
     * finite, even if the input is infinite.
     */
    result = atan(arg1);
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      atan2           - returns the arctan of arg1/arg2 (radians)
 */
Datum
datan2(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
    float8      result;
 
    /* Per the POSIX spec, return NaN if either input is NaN */
    if (isnan(arg1) || isnan(arg2))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /*
     * atan2 maps all inputs to values in the range [-Pi, Pi], so the result
     * should always be finite, even if the inputs are infinite.
     */
    result = atan2(arg1, arg2);
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dcos            - returns the cosine of arg1 (radians)
 */
Datum
dcos(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /*
     * cos() is periodic and so theoretically can work for all finite inputs,
     * but some implementations may choose to throw error if the input is so
     * large that there are no significant digits in the result.  So we should
     * check for errors.  POSIX allows an error to be reported either via
     * errno or via fetestexcept(), but currently we only support checking
     * errno.  (fetestexcept() is rumored to report underflow unreasonably
     * early on some platforms, so it's not clear that believing it would be a
     * net improvement anyway.)
     *
     * For infinite inputs, POSIX specifies that the trigonometric functions
     * should return a domain error; but we won't notice that unless the
     * platform reports via errno, so also explicitly test for infinite
     * inputs.
     */
    errno = 0;
    result = cos(arg1);
    if (errno != 0 || isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dcot            - returns the cotangent of arg1 (radians)
 */
Datum
dcot(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /* Be sure to throw an error if the input is infinite --- see dcos() */
    errno = 0;
    result = tan(arg1);
    if (errno != 0 || isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    result = 1.0 / result;
    /* Not checking for overflow because cot(0) == Inf */
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dsin            - returns the sine of arg1 (radians)
 */
Datum
dsin(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /* Be sure to throw an error if the input is infinite --- see dcos() */
    errno = 0;
    result = sin(arg1);
    if (errno != 0 || isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dtan            - returns the tangent of arg1 (radians)
 */
Datum
dtan(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    /* Be sure to throw an error if the input is infinite --- see dcos() */
    errno = 0;
    result = tan(arg1);
    if (errno != 0 || isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
    /* Not checking for overflow because tan(pi/2) == Inf */
 
    PG_RETURN_FLOAT8(result);
}
 
 
/* ========== DEGREE-BASED TRIGONOMETRIC FUNCTIONS ========== */
 
 
/*
 * Initialize the cached constants declared at the head of this file
 * (sin_30 etc).  The fact that we need those at all, let alone need this
 * Rube-Goldberg-worthy method of initializing them, is because there are
 * compilers out there that will precompute expressions such as sin(constant)
 * using a sin() function different from what will be used at runtime.  If we
 * want exact results, we must ensure that none of the scaling constants used
 * in the degree-based trig functions are computed that way.  To do so, we
 * compute them from the variables degree_c_thirty etc, which are also really
 * constants, but the compiler cannot assume that.
 *
 * Other hazards we are trying to forestall with this kluge include the
 * possibility that compilers will rearrange the expressions, or compute
 * some intermediate results in registers wider than a standard double.
 *
 * In the places where we use these constants, the typical pattern is like
 *      volatile float8 sin_x = sin(x * RADIANS_PER_DEGREE);
 *      return (sin_x / sin_30);
 * where we hope to get a value of exactly 1.0 from the division when x = 30.
 * The volatile temporary variable is needed on machines with wide float
 * registers, to ensure that the result of sin(x) is rounded to double width
 * the same as the value of sin_30 has been.  Experimentation with gcc shows
 * that marking the temp variable volatile is necessary to make the store and
 * reload actually happen; hopefully the same trick works for other compilers.
 * (gcc's documentation suggests using the -ffloat-store compiler switch to
 * ensure this, but that is compiler-specific and it also pessimizes code in
 * many places where we don't care about this.)
 */
static void
init_degree_constants(void)
{
    sin_30 = sin(degree_c_thirty * RADIANS_PER_DEGREE);
    one_minus_cos_60 = 1.0 - cos(degree_c_sixty * RADIANS_PER_DEGREE);
    asin_0_5 = asin(degree_c_one_half);
    acos_0_5 = acos(degree_c_one_half);
    atan_1_0 = atan(degree_c_one);
    tan_45 = sind_q1(degree_c_forty_five) / cosd_q1(degree_c_forty_five);
    cot_45 = cosd_q1(degree_c_forty_five) / sind_q1(degree_c_forty_five);
    degree_consts_set = true;
}
 
#define INIT_DEGREE_CONSTANTS() \
do { \
    if (!degree_consts_set) \
        init_degree_constants(); \
} while(0)
 
 
/*
 *      asind_q1        - returns the inverse sine of x in degrees, for x in
 *                        the range [0, 1].  The result is an angle in the
 *                        first quadrant --- [0, 90] degrees.
 *
 *                        For the 3 special case inputs (0, 0.5 and 1), this
 *                        function will return exact values (0, 30 and 90
 *                        degrees respectively).
 */
static double
asind_q1(double x)
{
    /*
     * Stitch together inverse sine and cosine functions for the ranges [0,
     * 0.5] and (0.5, 1].  Each expression below is guaranteed to return
     * exactly 30 for x=0.5, so the result is a continuous monotonic function
     * over the full range.
     */
    if (x <= 0.5)
    {
        volatile float8 asin_x = asin(x);
 
        return (asin_x / asin_0_5) * 30.0;
    }
    else
    {
        volatile float8 acos_x = acos(x);
 
        return 90.0 - (acos_x / acos_0_5) * 60.0;
    }
}
 
 
/*
 *      acosd_q1        - returns the inverse cosine of x in degrees, for x in
 *                        the range [0, 1].  The result is an angle in the
 *                        first quadrant --- [0, 90] degrees.
 *
 *                        For the 3 special case inputs (0, 0.5 and 1), this
 *                        function will return exact values (0, 60 and 90
 *                        degrees respectively).
 */
static double
acosd_q1(double x)
{
    /*
     * Stitch together inverse sine and cosine functions for the ranges [0,
     * 0.5] and (0.5, 1].  Each expression below is guaranteed to return
     * exactly 60 for x=0.5, so the result is a continuous monotonic function
     * over the full range.
     */
    if (x <= 0.5)
    {
        volatile float8 asin_x = asin(x);
 
        return 90.0 - (asin_x / asin_0_5) * 30.0;
    }
    else
    {
        volatile float8 acos_x = acos(x);
 
        return (acos_x / acos_0_5) * 60.0;
    }
}
 
 
/*
 *      dacosd          - returns the arccos of arg1 (degrees)
 */
Datum
dacosd(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    INIT_DEGREE_CONSTANTS();
 
    /*
     * The principal branch of the inverse cosine function maps values in the
     * range [-1, 1] to values in the range [0, 180], so we should reject any
     * inputs outside that range and the result will always be finite.
     */
    if (arg1 < -1.0 || arg1 > 1.0)
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    if (arg1 >= 0.0)
        result = acosd_q1(arg1);
    else
        result = 90.0 + asind_q1(-arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dasind          - returns the arcsin of arg1 (degrees)
 */
Datum
dasind(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    INIT_DEGREE_CONSTANTS();
 
    /*
     * The principal branch of the inverse sine function maps values in the
     * range [-1, 1] to values in the range [-90, 90], so we should reject any
     * inputs outside that range and the result will always be finite.
     */
    if (arg1 < -1.0 || arg1 > 1.0)
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    if (arg1 >= 0.0)
        result = asind_q1(arg1);
    else
        result = -asind_q1(-arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      datand          - returns the arctan of arg1 (degrees)
 */
Datum
datand(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
    volatile float8 atan_arg1;
 
    /* Per the POSIX spec, return NaN if the input is NaN */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    INIT_DEGREE_CONSTANTS();
 
    /*
     * The principal branch of the inverse tangent function maps all inputs to
     * values in the range [-90, 90], so the result should always be finite,
     * even if the input is infinite.  Additionally, we take care to ensure
     * than when arg1 is 1, the result is exactly 45.
     */
    atan_arg1 = atan(arg1);
    result = (atan_arg1 / atan_1_0) * 45.0;
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      atan2d          - returns the arctan of arg1/arg2 (degrees)
 */
Datum
datan2d(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
    float8      result;
    volatile float8 atan2_arg1_arg2;
 
    /* Per the POSIX spec, return NaN if either input is NaN */
    if (isnan(arg1) || isnan(arg2))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    INIT_DEGREE_CONSTANTS();
 
    /*
     * atan2d maps all inputs to values in the range [-180, 180], so the
     * result should always be finite, even if the inputs are infinite.
     *
     * Note: this coding assumes that atan(1.0) is a suitable scaling constant
     * to get an exact result from atan2().  This might well fail on us at
     * some point, requiring us to decide exactly what inputs we think we're
     * going to guarantee an exact result for.
     */
    atan2_arg1_arg2 = atan2(arg1, arg2);
    result = (atan2_arg1_arg2 / atan_1_0) * 45.0;
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      sind_0_to_30    - returns the sine of an angle that lies between 0 and
 *                        30 degrees.  This will return exactly 0 when x is 0,
 *                        and exactly 0.5 when x is 30 degrees.
 */
static double
sind_0_to_30(double x)
{
    volatile float8 sin_x = sin(x * RADIANS_PER_DEGREE);
 
    return (sin_x / sin_30) / 2.0;
}
 
 
/*
 *      cosd_0_to_60    - returns the cosine of an angle that lies between 0
 *                        and 60 degrees.  This will return exactly 1 when x
 *                        is 0, and exactly 0.5 when x is 60 degrees.
 */
static double
cosd_0_to_60(double x)
{
    volatile float8 one_minus_cos_x = 1.0 - cos(x * RADIANS_PER_DEGREE);
 
    return 1.0 - (one_minus_cos_x / one_minus_cos_60) / 2.0;
}
 
 
/*
 *      sind_q1         - returns the sine of an angle in the first quadrant
 *                        (0 to 90 degrees).
 */
static double
sind_q1(double x)
{
    /*
     * Stitch together the sine and cosine functions for the ranges [0, 30]
     * and (30, 90].  These guarantee to return exact answers at their
     * endpoints, so the overall result is a continuous monotonic function
     * that gives exact results when x = 0, 30 and 90 degrees.
     */
    if (x <= 30.0)
        return sind_0_to_30(x);
    else
        return cosd_0_to_60(90.0 - x);
}
 
 
/*
 *      cosd_q1         - returns the cosine of an angle in the first quadrant
 *                        (0 to 90 degrees).
 */
static double
cosd_q1(double x)
{
    /*
     * Stitch together the sine and cosine functions for the ranges [0, 60]
     * and (60, 90].  These guarantee to return exact answers at their
     * endpoints, so the overall result is a continuous monotonic function
     * that gives exact results when x = 0, 60 and 90 degrees.
     */
    if (x <= 60.0)
        return cosd_0_to_60(x);
    else
        return sind_0_to_30(90.0 - x);
}
 
 
/*
 *      dcosd           - returns the cosine of arg1 (degrees)
 */
Datum
dcosd(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
    int         sign = 1;
 
    /*
     * Per the POSIX spec, return NaN if the input is NaN and throw an error
     * if the input is infinite.
     */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    if (isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    INIT_DEGREE_CONSTANTS();
 
    /* Reduce the range of the input to [0,90] degrees */
    arg1 = fmod(arg1, 360.0);
 
    if (arg1 < 0.0)
    {
        /* cosd(-x) = cosd(x) */
        arg1 = -arg1;
    }
 
    if (arg1 > 180.0)
    {
        /* cosd(360-x) = cosd(x) */
        arg1 = 360.0 - arg1;
    }
 
    if (arg1 > 90.0)
    {
        /* cosd(180-x) = -cosd(x) */
        arg1 = 180.0 - arg1;
        sign = -sign;
    }
 
    result = sign * cosd_q1(arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dcotd           - returns the cotangent of arg1 (degrees)
 */
Datum
dcotd(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
    volatile float8 cot_arg1;
    int         sign = 1;
 
    /*
     * Per the POSIX spec, return NaN if the input is NaN and throw an error
     * if the input is infinite.
     */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    if (isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    INIT_DEGREE_CONSTANTS();
 
    /* Reduce the range of the input to [0,90] degrees */
    arg1 = fmod(arg1, 360.0);
 
    if (arg1 < 0.0)
    {
        /* cotd(-x) = -cotd(x) */
        arg1 = -arg1;
        sign = -sign;
    }
 
    if (arg1 > 180.0)
    {
        /* cotd(360-x) = -cotd(x) */
        arg1 = 360.0 - arg1;
        sign = -sign;
    }
 
    if (arg1 > 90.0)
    {
        /* cotd(180-x) = -cotd(x) */
        arg1 = 180.0 - arg1;
        sign = -sign;
    }
 
    cot_arg1 = cosd_q1(arg1) / sind_q1(arg1);
    result = sign * (cot_arg1 / cot_45);
 
    /*
     * On some machines we get cotd(270) = minus zero, but this isn't always
     * true.  For portability, and because the user constituency for this
     * function probably doesn't want minus zero, force it to plain zero.
     */
    if (result == 0.0)
        result = 0.0;
 
    /* Not checking for overflow because cotd(0) == Inf */
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dsind           - returns the sine of arg1 (degrees)
 */
Datum
dsind(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
    int         sign = 1;
 
    /*
     * Per the POSIX spec, return NaN if the input is NaN and throw an error
     * if the input is infinite.
     */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    if (isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    INIT_DEGREE_CONSTANTS();
 
    /* Reduce the range of the input to [0,90] degrees */
    arg1 = fmod(arg1, 360.0);
 
    if (arg1 < 0.0)
    {
        /* sind(-x) = -sind(x) */
        arg1 = -arg1;
        sign = -sign;
    }
 
    if (arg1 > 180.0)
    {
        /* sind(360-x) = -sind(x) */
        arg1 = 360.0 - arg1;
        sign = -sign;
    }
 
    if (arg1 > 90.0)
    {
        /* sind(180-x) = sind(x) */
        arg1 = 180.0 - arg1;
    }
 
    result = sign * sind_q1(arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dtand           - returns the tangent of arg1 (degrees)
 */
Datum
dtand(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
    volatile float8 tan_arg1;
    int         sign = 1;
 
    /*
     * Per the POSIX spec, return NaN if the input is NaN and throw an error
     * if the input is infinite.
     */
    if (isnan(arg1))
        PG_RETURN_FLOAT8(get_float8_nan());
 
    if (isinf(arg1))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    INIT_DEGREE_CONSTANTS();
 
    /* Reduce the range of the input to [0,90] degrees */
    arg1 = fmod(arg1, 360.0);
 
    if (arg1 < 0.0)
    {
        /* tand(-x) = -tand(x) */
        arg1 = -arg1;
        sign = -sign;
    }
 
    if (arg1 > 180.0)
    {
        /* tand(360-x) = -tand(x) */
        arg1 = 360.0 - arg1;
        sign = -sign;
    }
 
    if (arg1 > 90.0)
    {
        /* tand(180-x) = -tand(x) */
        arg1 = 180.0 - arg1;
        sign = -sign;
    }
 
    tan_arg1 = sind_q1(arg1) / cosd_q1(arg1);
    result = sign * (tan_arg1 / tan_45);
 
    /*
     * On some machines we get tand(180) = minus zero, but this isn't always
     * true.  For portability, and because the user constituency for this
     * function probably doesn't want minus zero, force it to plain zero.
     */
    if (result == 0.0)
        result = 0.0;
 
    /* Not checking for overflow because tand(90) == Inf */
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      degrees     - returns degrees converted from radians
 */
Datum
degrees(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(float8_div(arg1, RADIANS_PER_DEGREE));
}
 
 
/*
 *      dpi             - returns the constant PI
 */
Datum
dpi(PG_FUNCTION_ARGS)
{
    PG_RETURN_FLOAT8(M_PI);
}
 
 
/*
 *      radians     - returns radians converted from degrees
 */
Datum
radians(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
 
    PG_RETURN_FLOAT8(float8_mul(arg1, RADIANS_PER_DEGREE));
}
 
 
/* ========== HYPERBOLIC FUNCTIONS ========== */
 
 
/*
 *      dsinh           - returns the hyperbolic sine of arg1
 */
Datum
dsinh(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    errno = 0;
    result = sinh(arg1);
 
    /*
     * if an ERANGE error occurs, it means there is an overflow.  For sinh,
     * the result should be either -infinity or infinity, depending on the
     * sign of arg1.
     */
    if (errno == ERANGE)
    {
        if (arg1 < 0)
            result = -get_float8_infinity();
        else
            result = get_float8_infinity();
    }
 
    PG_RETURN_FLOAT8(result);
}
 
 
/*
 *      dcosh           - returns the hyperbolic cosine of arg1
 */
Datum
dcosh(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    errno = 0;
    result = cosh(arg1);
 
    /*
     * if an ERANGE error occurs, it means there is an overflow.  As cosh is
     * always positive, it always means the result is positive infinity.
     */
    if (errno == ERANGE)
        result = get_float8_infinity();
 
    if (unlikely(result == 0.0))
        float_underflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      dtanh           - returns the hyperbolic tangent of arg1
 */
Datum
dtanh(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * For tanh, we don't need an errno check because it never overflows.
     */
    result = tanh(arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      dasinh          - returns the inverse hyperbolic sine of arg1
 */
Datum
dasinh(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * For asinh, we don't need an errno check because it never overflows.
     */
    result = asinh(arg1);
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      dacosh          - returns the inverse hyperbolic cosine of arg1
 */
Datum
dacosh(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * acosh is only defined for inputs >= 1.0.  By checking this ourselves,
     * we need not worry about checking for an EDOM error, which is a good
     * thing because some implementations will report that for NaN. Otherwise,
     * no error is possible.
     */
    if (arg1 < 1.0)
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    result = acosh(arg1);
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      datanh          - returns the inverse hyperbolic tangent of arg1
 */
Datum
datanh(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * atanh is only defined for inputs between -1 and 1.  By checking this
     * ourselves, we need not worry about checking for an EDOM error, which is
     * a good thing because some implementations will report that for NaN.
     */
    if (arg1 < -1.0 || arg1 > 1.0)
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 errmsg("input is out of range")));
 
    /*
     * Also handle the infinity cases ourselves; this is helpful because old
     * glibc versions may produce the wrong errno for this.  All other inputs
     * cannot produce an error.
     */
    if (arg1 == -1.0)
        result = -get_float8_infinity();
    else if (arg1 == 1.0)
        result = get_float8_infinity();
    else
        result = atanh(arg1);
 
    PG_RETURN_FLOAT8(result);
}
 
 
/* ========== ERROR FUNCTIONS ========== */
 
 
/*
 *      derf            - returns the error function: erf(arg1)
 */
Datum
derf(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * For erf, we don't need an errno check because it never overflows.
     */
    result = erf(arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      derfc           - returns the complementary error function: 1 - erf(arg1)
 */
Datum
derfc(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float8      result;
 
    /*
     * For erfc, we don't need an errno check because it never overflows.
     */
    result = erfc(arg1);
 
    if (unlikely(isinf(result)))
        float_overflow_error();
 
    PG_RETURN_FLOAT8(result);
}
 
 
/* ========== RANDOM FUNCTIONS ========== */
 
 
/*
 * initialize_drandom_seed - initialize drandom_seed if not yet done
 */
static void
initialize_drandom_seed(void)
{
    /* Initialize random seed, if not done yet in this process */
    if (unlikely(!drandom_seed_set))
    {
        /*
         * If possible, initialize the seed using high-quality random bits.
         * Should that fail for some reason, we fall back on a lower-quality
         * seed based on current time and PID.
         */
        if (unlikely(!pg_prng_strong_seed(&drandom_seed)))
        {
            TimestampTz now = GetCurrentTimestamp();
            uint64      iseed;
 
            /* Mix the PID with the most predictable bits of the timestamp */
            iseed = (uint64) now ^ ((uint64) MyProcPid << 32);
            pg_prng_seed(&drandom_seed, iseed);
        }
        drandom_seed_set = true;
    }
}
 
/*
 *      drandom     - returns a random number
 */
Datum
drandom(PG_FUNCTION_ARGS)
{
    float8      result;
 
    initialize_drandom_seed();
 
    /* pg_prng_double produces desired result range [0.0 - 1.0) */
    result = pg_prng_double(&drandom_seed);
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      drandom_normal  - returns a random number from a normal distribution
 */
Datum
drandom_normal(PG_FUNCTION_ARGS)
{
    float8      mean = PG_GETARG_FLOAT8(0);
    float8      stddev = PG_GETARG_FLOAT8(1);
    float8      result,
                z;
 
    initialize_drandom_seed();
 
    /* Get random value from standard normal(mean = 0.0, stddev = 1.0) */
    z = pg_prng_double_normal(&drandom_seed);
    /* Transform the normal standard variable (z) */
    /* using the target normal distribution parameters */
    result = (stddev * z) + mean;
 
    PG_RETURN_FLOAT8(result);
}
 
/*
 *      setseed     - set seed for the random number generator
 */
Datum
setseed(PG_FUNCTION_ARGS)
{
    float8      seed = PG_GETARG_FLOAT8(0);
 
    if (seed < -1 || seed > 1 || isnan(seed))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("setseed parameter %g is out of allowed range [-1,1]",
                        seed)));
 
    pg_prng_fseed(&drandom_seed, seed);
    drandom_seed_set = true;
 
    PG_RETURN_VOID();
}
 
 
 
/*
 *      =========================
 *      FLOAT AGGREGATE OPERATORS
 *      =========================
 *
 *      float8_accum        - accumulate for AVG(), variance aggregates, etc.
 *      float4_accum        - same, but input data is float4
 *      float8_avg          - produce final result for float AVG()
 *      float8_var_samp     - produce final result for float VAR_SAMP()
 *      float8_var_pop      - produce final result for float VAR_POP()
 *      float8_stddev_samp  - produce final result for float STDDEV_SAMP()
 *      float8_stddev_pop   - produce final result for float STDDEV_POP()
 *
 * The naive schoolbook implementation of these aggregates works by
 * accumulating sum(X) and sum(X^2).  However, this approach suffers from
 * large rounding errors in the final computation of quantities like the
 * population variance (N*sum(X^2) - sum(X)^2) / N^2, since each of the
 * intermediate terms is potentially very large, while the difference is often
 * quite small.
 *
 * Instead we use the Youngs-Cramer algorithm [1] which works by accumulating
 * Sx=sum(X) and Sxx=sum((X-Sx/N)^2), using a numerically stable algorithm to
 * incrementally update those quantities.  The final computations of each of
 * the aggregate values is then trivial and gives more accurate results (for
 * example, the population variance is just Sxx/N).  This algorithm is also
 * fairly easy to generalize to allow parallel execution without loss of
 * precision (see, for example, [2]).  For more details, and a comparison of
 * this with other algorithms, see [3].
 *
 * The transition datatype for all these aggregates is a 3-element array
 * of float8, holding the values N, Sx, Sxx in that order.
 *
 * Note that we represent N as a float to avoid having to build a special
 * datatype.  Given a reasonable floating-point implementation, there should
 * be no accuracy loss unless N exceeds 2 ^ 52 or so (by which time the
 * user will have doubtless lost interest anyway...)
 *
 * [1] Some Results Relevant to Choice of Sum and Sum-of-Product Algorithms,
 * E. A. Youngs and E. M. Cramer, Technometrics Vol 13, No 3, August 1971.
 *
 * [2] Updating Formulae and a Pairwise Algorithm for Computing Sample
 * Variances, T. F. Chan, G. H. Golub & R. J. LeVeque, COMPSTAT 1982.
 *
 * [3] Numerically Stable Parallel Computation of (Co-)Variance, Erich
 * Schubert and Michael Gertz, Proceedings of the 30th International
 * Conference on Scientific and Statistical Database Management, 2018.
 */
 
static float8 *
check_float8_array(ArrayType *transarray, const char *caller, int n)
{
    /*
     * We expect the input to be an N-element float array; verify that. We
     * don't need to use deconstruct_array() since the array data is just
     * going to look like a C array of N float8 values.
     */
    if (ARR_NDIM(transarray) != 1 ||
        ARR_DIMS(transarray)[0] != n ||
        ARR_HASNULL(transarray) ||
        ARR_ELEMTYPE(transarray) != FLOAT8OID)
        elog(ERROR, "%s: expected %d-element float8 array", caller, n);
    return (float8 *) ARR_DATA_PTR(transarray);
}
 
/*
 * float8_combine
 *
 * An aggregate combine function used to combine two 3 fields
 * aggregate transition data into a single transition data.
 * This function is used only in two stage aggregation and
 * shouldn't be called outside aggregate context.
 */
Datum
float8_combine(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *transarray2 = PG_GETARG_ARRAYTYPE_P(1);
    float8     *transvalues1;
    float8     *transvalues2;
    float8      N1,
                Sx1,
                Sxx1,
                N2,
                Sx2,
                Sxx2,
                tmp,
                N,
                Sx,
                Sxx;
 
    transvalues1 = check_float8_array(transarray1, "float8_combine", 3);
    transvalues2 = check_float8_array(transarray2, "float8_combine", 3);
 
    N1 = transvalues1[0];
    Sx1 = transvalues1[1];
    Sxx1 = transvalues1[2];
 
    N2 = transvalues2[0];
    Sx2 = transvalues2[1];
    Sxx2 = transvalues2[2];
 
    /*--------------------
     * The transition values combine using a generalization of the
     * Youngs-Cramer algorithm as follows:
     *
     *  N = N1 + N2
     *  Sx = Sx1 + Sx2
     *  Sxx = Sxx1 + Sxx2 + N1 * N2 * (Sx1/N1 - Sx2/N2)^2 / N;
     *
     * It's worth handling the special cases N1 = 0 and N2 = 0 separately
     * since those cases are trivial, and we then don't need to worry about
     * division-by-zero errors in the general case.
     *--------------------
     */
    if (N1 == 0.0)
    {
        N = N2;
        Sx = Sx2;
        Sxx = Sxx2;
    }
    else if (N2 == 0.0)
    {
        N = N1;
        Sx = Sx1;
        Sxx = Sxx1;
    }
    else
    {
        N = N1 + N2;
        Sx = float8_pl(Sx1, Sx2);
        tmp = Sx1 / N1 - Sx2 / N2;
        Sxx = Sxx1 + Sxx2 + N1 * N2 * tmp * tmp / N;
        if (unlikely(isinf(Sxx)) && !isinf(Sxx1) && !isinf(Sxx2))
            float_overflow_error();
    }
 
    /*
     * If we're invoked as an aggregate, we can cheat and modify our first
     * parameter in-place to reduce palloc overhead. Otherwise we construct a
     * new array with the updated transition data and return it.
     */
    if (AggCheckCallContext(fcinfo, NULL))
    {
        transvalues1[0] = N;
        transvalues1[1] = Sx;
        transvalues1[2] = Sxx;
 
        PG_RETURN_ARRAYTYPE_P(transarray1);
    }
    else
    {
        Datum       transdatums[3];
        ArrayType  *result;
 
        transdatums[0] = Float8GetDatumFast(N);
        transdatums[1] = Float8GetDatumFast(Sx);
        transdatums[2] = Float8GetDatumFast(Sxx);
 
        result = construct_array(transdatums, 3,
                                 FLOAT8OID,
                                 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
 
        PG_RETURN_ARRAYTYPE_P(result);
    }
}
 
Datum
float8_accum(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8      newval = PG_GETARG_FLOAT8(1);
    float8     *transvalues;
    float8      N,
                Sx,
                Sxx,
                tmp;
 
    transvalues = check_float8_array(transarray, "float8_accum", 3);
    N = transvalues[0];
    Sx = transvalues[1];
    Sxx = transvalues[2];
 
    /*
     * Use the Youngs-Cramer algorithm to incorporate the new value into the
     * transition values.
     */
    N += 1.0;
    Sx += newval;
    if (transvalues[0] > 0.0)
    {
        tmp = newval * N - Sx;
        Sxx += tmp * tmp / (N * transvalues[0]);
 
        /*
         * Overflow check.  We only report an overflow error when finite
         * inputs lead to infinite results.  Note also that Sxx should be NaN
         * if any of the inputs are infinite, so we intentionally prevent Sxx
         * from becoming infinite.
         */
        if (isinf(Sx) || isinf(Sxx))
        {
            if (!isinf(transvalues[1]) && !isinf(newval))
                float_overflow_error();
 
            Sxx = get_float8_nan();
        }
    }
    else
    {
        /*
         * At the first input, we normally can leave Sxx as 0.  However, if
         * the first input is Inf or NaN, we'd better force Sxx to NaN;
         * otherwise we will falsely report variance zero when there are no
         * more inputs.
         */
        if (isnan(newval) || isinf(newval))
            Sxx = get_float8_nan();
    }
 
    /*
     * If we're invoked as an aggregate, we can cheat and modify our first
     * parameter in-place to reduce palloc overhead. Otherwise we construct a
     * new array with the updated transition data and return it.
     */
    if (AggCheckCallContext(fcinfo, NULL))
    {
        transvalues[0] = N;
        transvalues[1] = Sx;
        transvalues[2] = Sxx;
 
        PG_RETURN_ARRAYTYPE_P(transarray);
    }
    else
    {
        Datum       transdatums[3];
        ArrayType  *result;
 
        transdatums[0] = Float8GetDatumFast(N);
        transdatums[1] = Float8GetDatumFast(Sx);
        transdatums[2] = Float8GetDatumFast(Sxx);
 
        result = construct_array(transdatums, 3,
                                 FLOAT8OID,
                                 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
 
        PG_RETURN_ARRAYTYPE_P(result);
    }
}
 
Datum
float4_accum(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
 
    /* do computations as float8 */
    float8      newval = PG_GETARG_FLOAT4(1);
    float8     *transvalues;
    float8      N,
                Sx,
                Sxx,
                tmp;
 
    transvalues = check_float8_array(transarray, "float4_accum", 3);
    N = transvalues[0];
    Sx = transvalues[1];
    Sxx = transvalues[2];
 
    /*
     * Use the Youngs-Cramer algorithm to incorporate the new value into the
     * transition values.
     */
    N += 1.0;
    Sx += newval;
    if (transvalues[0] > 0.0)
    {
        tmp = newval * N - Sx;
        Sxx += tmp * tmp / (N * transvalues[0]);
 
        /*
         * Overflow check.  We only report an overflow error when finite
         * inputs lead to infinite results.  Note also that Sxx should be NaN
         * if any of the inputs are infinite, so we intentionally prevent Sxx
         * from becoming infinite.
         */
        if (isinf(Sx) || isinf(Sxx))
        {
            if (!isinf(transvalues[1]) && !isinf(newval))
                float_overflow_error();
 
            Sxx = get_float8_nan();
        }
    }
    else
    {
        /*
         * At the first input, we normally can leave Sxx as 0.  However, if
         * the first input is Inf or NaN, we'd better force Sxx to NaN;
         * otherwise we will falsely report variance zero when there are no
         * more inputs.
         */
        if (isnan(newval) || isinf(newval))
            Sxx = get_float8_nan();
    }
 
    /*
     * If we're invoked as an aggregate, we can cheat and modify our first
     * parameter in-place to reduce palloc overhead. Otherwise we construct a
     * new array with the updated transition data and return it.
     */
    if (AggCheckCallContext(fcinfo, NULL))
    {
        transvalues[0] = N;
        transvalues[1] = Sx;
        transvalues[2] = Sxx;
 
        PG_RETURN_ARRAYTYPE_P(transarray);
    }
    else
    {
        Datum       transdatums[3];
        ArrayType  *result;
 
        transdatums[0] = Float8GetDatumFast(N);
        transdatums[1] = Float8GetDatumFast(Sx);
        transdatums[2] = Float8GetDatumFast(Sxx);
 
        result = construct_array(transdatums, 3,
                                 FLOAT8OID,
                                 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
 
        PG_RETURN_ARRAYTYPE_P(result);
    }
}
 
Datum
float8_avg(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sx;
 
    transvalues = check_float8_array(transarray, "float8_avg", 3);
    N = transvalues[0];
    Sx = transvalues[1];
    /* ignore Sxx */
 
    /* SQL defines AVG of no values to be NULL */
    if (N == 0.0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sx / N);
}
 
Datum
float8_var_pop(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx;
 
    transvalues = check_float8_array(transarray, "float8_var_pop", 3);
    N = transvalues[0];
    /* ignore Sx */
    Sxx = transvalues[2];
 
    /* Population variance is undefined when N is 0, so return NULL */
    if (N == 0.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    PG_RETURN_FLOAT8(Sxx / N);
}
 
Datum
float8_var_samp(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx;
 
    transvalues = check_float8_array(transarray, "float8_var_samp", 3);
    N = transvalues[0];
    /* ignore Sx */
    Sxx = transvalues[2];
 
    /* Sample variance is undefined when N is 0 or 1, so return NULL */
    if (N <= 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    PG_RETURN_FLOAT8(Sxx / (N - 1.0));
}
 
Datum
float8_stddev_pop(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx;
 
    transvalues = check_float8_array(transarray, "float8_stddev_pop", 3);
    N = transvalues[0];
    /* ignore Sx */
    Sxx = transvalues[2];
 
    /* Population stddev is undefined when N is 0, so return NULL */
    if (N == 0.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    PG_RETURN_FLOAT8(sqrt(Sxx / N));
}
 
Datum
float8_stddev_samp(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx;
 
    transvalues = check_float8_array(transarray, "float8_stddev_samp", 3);
    N = transvalues[0];
    /* ignore Sx */
    Sxx = transvalues[2];
 
    /* Sample stddev is undefined when N is 0 or 1, so return NULL */
    if (N <= 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    PG_RETURN_FLOAT8(sqrt(Sxx / (N - 1.0)));
}
 
/*
 *      =========================
 *      SQL2003 BINARY AGGREGATES
 *      =========================
 *
 * As with the preceding aggregates, we use the Youngs-Cramer algorithm to
 * reduce rounding errors in the aggregate final functions.
 *
 * The transition datatype for all these aggregates is a 6-element array of
 * float8, holding the values N, Sx=sum(X), Sxx=sum((X-Sx/N)^2), Sy=sum(Y),
 * Syy=sum((Y-Sy/N)^2), Sxy=sum((X-Sx/N)*(Y-Sy/N)) in that order.
 *
 * Note that Y is the first argument to all these aggregates!
 *
 * It might seem attractive to optimize this by having multiple accumulator
 * functions that only calculate the sums actually needed.  But on most
 * modern machines, a couple of extra floating-point multiplies will be
 * insignificant compared to the other per-tuple overhead, so I've chosen
 * to minimize code space instead.
 */
 
Datum
float8_regr_accum(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8      newvalY = PG_GETARG_FLOAT8(1);
    float8      newvalX = PG_GETARG_FLOAT8(2);
    float8     *transvalues;
    float8      N,
                Sx,
                Sxx,
                Sy,
                Syy,
                Sxy,
                tmpX,
                tmpY,
                scale;
 
    transvalues = check_float8_array(transarray, "float8_regr_accum", 6);
    N = transvalues[0];
    Sx = transvalues[1];
    Sxx = transvalues[2];
    Sy = transvalues[3];
    Syy = transvalues[4];
    Sxy = transvalues[5];
 
    /*
     * Use the Youngs-Cramer algorithm to incorporate the new values into the
     * transition values.
     */
    N += 1.0;
    Sx += newvalX;
    Sy += newvalY;
    if (transvalues[0] > 0.0)
    {
        tmpX = newvalX * N - Sx;
        tmpY = newvalY * N - Sy;
        scale = 1.0 / (N * transvalues[0]);
        Sxx += tmpX * tmpX * scale;
        Syy += tmpY * tmpY * scale;
        Sxy += tmpX * tmpY * scale;
 
        /*
         * Overflow check.  We only report an overflow error when finite
         * inputs lead to infinite results.  Note also that Sxx, Syy and Sxy
         * should be NaN if any of the relevant inputs are infinite, so we
         * intentionally prevent them from becoming infinite.
         */
        if (isinf(Sx) || isinf(Sxx) || isinf(Sy) || isinf(Syy) || isinf(Sxy))
        {
            if (((isinf(Sx) || isinf(Sxx)) &&
                 !isinf(transvalues[1]) && !isinf(newvalX)) ||
                ((isinf(Sy) || isinf(Syy)) &&
                 !isinf(transvalues[3]) && !isinf(newvalY)) ||
                (isinf(Sxy) &&
                 !isinf(transvalues[1]) && !isinf(newvalX) &&
                 !isinf(transvalues[3]) && !isinf(newvalY)))
                float_overflow_error();
 
            if (isinf(Sxx))
                Sxx = get_float8_nan();
            if (isinf(Syy))
                Syy = get_float8_nan();
            if (isinf(Sxy))
                Sxy = get_float8_nan();
        }
    }
    else
    {
        /*
         * At the first input, we normally can leave Sxx et al as 0.  However,
         * if the first input is Inf or NaN, we'd better force the dependent
         * sums to NaN; otherwise we will falsely report variance zero when
         * there are no more inputs.
         */
        if (isnan(newvalX) || isinf(newvalX))
            Sxx = Sxy = get_float8_nan();
        if (isnan(newvalY) || isinf(newvalY))
            Syy = Sxy = get_float8_nan();
    }
 
    /*
     * If we're invoked as an aggregate, we can cheat and modify our first
     * parameter in-place to reduce palloc overhead. Otherwise we construct a
     * new array with the updated transition data and return it.
     */
    if (AggCheckCallContext(fcinfo, NULL))
    {
        transvalues[0] = N;
        transvalues[1] = Sx;
        transvalues[2] = Sxx;
        transvalues[3] = Sy;
        transvalues[4] = Syy;
        transvalues[5] = Sxy;
 
        PG_RETURN_ARRAYTYPE_P(transarray);
    }
    else
    {
        Datum       transdatums[6];
        ArrayType  *result;
 
        transdatums[0] = Float8GetDatumFast(N);
        transdatums[1] = Float8GetDatumFast(Sx);
        transdatums[2] = Float8GetDatumFast(Sxx);
        transdatums[3] = Float8GetDatumFast(Sy);
        transdatums[4] = Float8GetDatumFast(Syy);
        transdatums[5] = Float8GetDatumFast(Sxy);
 
        result = construct_array(transdatums, 6,
                                 FLOAT8OID,
                                 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
 
        PG_RETURN_ARRAYTYPE_P(result);
    }
}
 
/*
 * float8_regr_combine
 *
 * An aggregate combine function used to combine two 6 fields
 * aggregate transition data into a single transition data.
 * This function is used only in two stage aggregation and
 * shouldn't be called outside aggregate context.
 */
Datum
float8_regr_combine(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *transarray2 = PG_GETARG_ARRAYTYPE_P(1);
    float8     *transvalues1;
    float8     *transvalues2;
    float8      N1,
                Sx1,
                Sxx1,
                Sy1,
                Syy1,
                Sxy1,
                N2,
                Sx2,
                Sxx2,
                Sy2,
                Syy2,
                Sxy2,
                tmp1,
                tmp2,
                N,
                Sx,
                Sxx,
                Sy,
                Syy,
                Sxy;
 
    transvalues1 = check_float8_array(transarray1, "float8_regr_combine", 6);
    transvalues2 = check_float8_array(transarray2, "float8_regr_combine", 6);
 
    N1 = transvalues1[0];
    Sx1 = transvalues1[1];
    Sxx1 = transvalues1[2];
    Sy1 = transvalues1[3];
    Syy1 = transvalues1[4];
    Sxy1 = transvalues1[5];
 
    N2 = transvalues2[0];
    Sx2 = transvalues2[1];
    Sxx2 = transvalues2[2];
    Sy2 = transvalues2[3];
    Syy2 = transvalues2[4];
    Sxy2 = transvalues2[5];
 
    /*--------------------
     * The transition values combine using a generalization of the
     * Youngs-Cramer algorithm as follows:
     *
     *  N = N1 + N2
     *  Sx = Sx1 + Sx2
     *  Sxx = Sxx1 + Sxx2 + N1 * N2 * (Sx1/N1 - Sx2/N2)^2 / N
     *  Sy = Sy1 + Sy2
     *  Syy = Syy1 + Syy2 + N1 * N2 * (Sy1/N1 - Sy2/N2)^2 / N
     *  Sxy = Sxy1 + Sxy2 + N1 * N2 * (Sx1/N1 - Sx2/N2) * (Sy1/N1 - Sy2/N2) / N
     *
     * It's worth handling the special cases N1 = 0 and N2 = 0 separately
     * since those cases are trivial, and we then don't need to worry about
     * division-by-zero errors in the general case.
     *--------------------
     */
    if (N1 == 0.0)
    {
        N = N2;
        Sx = Sx2;
        Sxx = Sxx2;
        Sy = Sy2;
        Syy = Syy2;
        Sxy = Sxy2;
    }
    else if (N2 == 0.0)
    {
        N = N1;
        Sx = Sx1;
        Sxx = Sxx1;
        Sy = Sy1;
        Syy = Syy1;
        Sxy = Sxy1;
    }
    else
    {
        N = N1 + N2;
        Sx = float8_pl(Sx1, Sx2);
        tmp1 = Sx1 / N1 - Sx2 / N2;
        Sxx = Sxx1 + Sxx2 + N1 * N2 * tmp1 * tmp1 / N;
        if (unlikely(isinf(Sxx)) && !isinf(Sxx1) && !isinf(Sxx2))
            float_overflow_error();
        Sy = float8_pl(Sy1, Sy2);
        tmp2 = Sy1 / N1 - Sy2 / N2;
        Syy = Syy1 + Syy2 + N1 * N2 * tmp2 * tmp2 / N;
        if (unlikely(isinf(Syy)) && !isinf(Syy1) && !isinf(Syy2))
            float_overflow_error();
        Sxy = Sxy1 + Sxy2 + N1 * N2 * tmp1 * tmp2 / N;
        if (unlikely(isinf(Sxy)) && !isinf(Sxy1) && !isinf(Sxy2))
            float_overflow_error();
    }
 
    /*
     * If we're invoked as an aggregate, we can cheat and modify our first
     * parameter in-place to reduce palloc overhead. Otherwise we construct a
     * new array with the updated transition data and return it.
     */
    if (AggCheckCallContext(fcinfo, NULL))
    {
        transvalues1[0] = N;
        transvalues1[1] = Sx;
        transvalues1[2] = Sxx;
        transvalues1[3] = Sy;
        transvalues1[4] = Syy;
        transvalues1[5] = Sxy;
 
        PG_RETURN_ARRAYTYPE_P(transarray1);
    }
    else
    {
        Datum       transdatums[6];
        ArrayType  *result;
 
        transdatums[0] = Float8GetDatumFast(N);
        transdatums[1] = Float8GetDatumFast(Sx);
        transdatums[2] = Float8GetDatumFast(Sxx);
        transdatums[3] = Float8GetDatumFast(Sy);
        transdatums[4] = Float8GetDatumFast(Syy);
        transdatums[5] = Float8GetDatumFast(Sxy);
 
        result = construct_array(transdatums, 6,
                                 FLOAT8OID,
                                 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
 
        PG_RETURN_ARRAYTYPE_P(result);
    }
}
 
 
Datum
float8_regr_sxx(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx;
 
    transvalues = check_float8_array(transarray, "float8_regr_sxx", 6);
    N = transvalues[0];
    Sxx = transvalues[2];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    PG_RETURN_FLOAT8(Sxx);
}
 
Datum
float8_regr_syy(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Syy;
 
    transvalues = check_float8_array(transarray, "float8_regr_syy", 6);
    N = transvalues[0];
    Syy = transvalues[4];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* Note that Syy is guaranteed to be non-negative */
 
    PG_RETURN_FLOAT8(Syy);
}
 
Datum
float8_regr_sxy(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_regr_sxy", 6);
    N = transvalues[0];
    Sxy = transvalues[5];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* A negative result is valid here */
 
    PG_RETURN_FLOAT8(Sxy);
}
 
Datum
float8_regr_avgx(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sx;
 
    transvalues = check_float8_array(transarray, "float8_regr_avgx", 6);
    N = transvalues[0];
    Sx = transvalues[1];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sx / N);
}
 
Datum
float8_regr_avgy(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sy;
 
    transvalues = check_float8_array(transarray, "float8_regr_avgy", 6);
    N = transvalues[0];
    Sy = transvalues[3];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sy / N);
}
 
Datum
float8_covar_pop(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_covar_pop", 6);
    N = transvalues[0];
    Sxy = transvalues[5];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sxy / N);
}
 
Datum
float8_covar_samp(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_covar_samp", 6);
    N = transvalues[0];
    Sxy = transvalues[5];
 
    /* if N is <= 1 we should return NULL */
    if (N < 2.0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sxy / (N - 1.0));
}
 
Datum
float8_corr(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx,
                Syy,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_corr", 6);
    N = transvalues[0];
    Sxx = transvalues[2];
    Syy = transvalues[4];
    Sxy = transvalues[5];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx and Syy are guaranteed to be non-negative */
 
    /* per spec, return NULL for horizontal and vertical lines */
    if (Sxx == 0 || Syy == 0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sxy / sqrt(Sxx * Syy));
}
 
Datum
float8_regr_r2(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx,
                Syy,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_regr_r2", 6);
    N = transvalues[0];
    Sxx = transvalues[2];
    Syy = transvalues[4];
    Sxy = transvalues[5];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx and Syy are guaranteed to be non-negative */
 
    /* per spec, return NULL for a vertical line */
    if (Sxx == 0)
        PG_RETURN_NULL();
 
    /* per spec, return 1.0 for a horizontal line */
    if (Syy == 0)
        PG_RETURN_FLOAT8(1.0);
 
    PG_RETURN_FLOAT8((Sxy * Sxy) / (Sxx * Syy));
}
 
Datum
float8_regr_slope(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sxx,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_regr_slope", 6);
    N = transvalues[0];
    Sxx = transvalues[2];
    Sxy = transvalues[5];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    /* per spec, return NULL for a vertical line */
    if (Sxx == 0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8(Sxy / Sxx);
}
 
Datum
float8_regr_intercept(PG_FUNCTION_ARGS)
{
    ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
    float8     *transvalues;
    float8      N,
                Sx,
                Sxx,
                Sy,
                Sxy;
 
    transvalues = check_float8_array(transarray, "float8_regr_intercept", 6);
    N = transvalues[0];
    Sx = transvalues[1];
    Sxx = transvalues[2];
    Sy = transvalues[3];
    Sxy = transvalues[5];
 
    /* if N is 0 we should return NULL */
    if (N < 1.0)
        PG_RETURN_NULL();
 
    /* Note that Sxx is guaranteed to be non-negative */
 
    /* per spec, return NULL for a vertical line */
    if (Sxx == 0)
        PG_RETURN_NULL();
 
    PG_RETURN_FLOAT8((Sy - Sx * Sxy / Sxx) / N);
}
 
 
/*
 *      ====================================
 *      MIXED-PRECISION ARITHMETIC OPERATORS
 *      ====================================
 */
 
/*
 *      float48pl       - returns arg1 + arg2
 *      float48mi       - returns arg1 - arg2
 *      float48mul      - returns arg1 * arg2
 *      float48div      - returns arg1 / arg2
 */
Datum
float48pl(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_pl((float8) arg1, arg2));
}
 
Datum
float48mi(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_mi((float8) arg1, arg2));
}
 
Datum
float48mul(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_mul((float8) arg1, arg2));
}
 
Datum
float48div(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_FLOAT8(float8_div((float8) arg1, arg2));
}
 
/*
 *      float84pl       - returns arg1 + arg2
 *      float84mi       - returns arg1 - arg2
 *      float84mul      - returns arg1 * arg2
 *      float84div      - returns arg1 / arg2
 */
Datum
float84pl(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT8(float8_pl(arg1, (float8) arg2));
}
 
Datum
float84mi(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT8(float8_mi(arg1, (float8) arg2));
}
 
Datum
float84mul(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT8(float8_mul(arg1, (float8) arg2));
}
 
Datum
float84div(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_FLOAT8(float8_div(arg1, (float8) arg2));
}
 
/*
 *      ====================
 *      COMPARISON OPERATORS
 *      ====================
 */
 
/*
 *      float48{eq,ne,lt,le,gt,ge}      - float4/float8 comparison operations
 */
Datum
float48eq(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_eq((float8) arg1, arg2));
}
 
Datum
float48ne(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_ne((float8) arg1, arg2));
}
 
Datum
float48lt(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_lt((float8) arg1, arg2));
}
 
Datum
float48le(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_le((float8) arg1, arg2));
}
 
Datum
float48gt(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_gt((float8) arg1, arg2));
}
 
Datum
float48ge(PG_FUNCTION_ARGS)
{
    float4      arg1 = PG_GETARG_FLOAT4(0);
    float8      arg2 = PG_GETARG_FLOAT8(1);
 
    PG_RETURN_BOOL(float8_ge((float8) arg1, arg2));
}
 
/*
 *      float84{eq,ne,lt,le,gt,ge}      - float8/float4 comparison operations
 */
Datum
float84eq(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float8_eq(arg1, (float8) arg2));
}
 
Datum
float84ne(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float8_ne(arg1, (float8) arg2));
}
 
Datum
float84lt(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float8_lt(arg1, (float8) arg2));
}
 
Datum
float84le(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float8_le(arg1, (float8) arg2));
}
 
Datum
float84gt(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float8_gt(arg1, (float8) arg2));
}
 
Datum
float84ge(PG_FUNCTION_ARGS)
{
    float8      arg1 = PG_GETARG_FLOAT8(0);
    float4      arg2 = PG_GETARG_FLOAT4(1);
 
    PG_RETURN_BOOL(float8_ge(arg1, (float8) arg2));
}
 
/*
 * Implements the float8 version of the width_bucket() function
 * defined by SQL2003. See also width_bucket_numeric().
 *
 * 'bound1' and 'bound2' are the lower and upper bounds of the
 * histogram's range, respectively. 'count' is the number of buckets
 * in the histogram. width_bucket() returns an integer indicating the
 * bucket number that 'operand' belongs to in an equiwidth histogram
 * with the specified characteristics. An operand smaller than the
 * lower bound is assigned to bucket 0. An operand greater than the
 * upper bound is assigned to an additional bucket (with number
 * count+1). We don't allow "NaN" for any of the float8 inputs, and we
 * don't allow either of the histogram bounds to be +/- infinity.
 */
Datum
width_bucket_float8(PG_FUNCTION_ARGS)
{
    float8      operand = PG_GETARG_FLOAT8(0);
    float8      bound1 = PG_GETARG_FLOAT8(1);
    float8      bound2 = PG_GETARG_FLOAT8(2);
    int32       count = PG_GETARG_INT32(3);
    int32       result;
 
    if (count <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
                 errmsg("count must be greater than zero")));
 
    if (isnan(operand) || isnan(bound1) || isnan(bound2))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
                 errmsg("operand, lower bound, and upper bound cannot be NaN")));
 
    /* Note that we allow "operand" to be infinite */
    if (isinf(bound1) || isinf(bound2))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
                 errmsg("lower and upper bounds must be finite")));
 
    if (bound1 < bound2)
    {
        if (operand < bound1)
            result = 0;
        else if (operand >= bound2)
        {
            if (pg_add_s32_overflow(count, 1, &result))
                ereport(ERROR,
                        (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                         errmsg("integer out of range")));
        }
        else
        {
            if (!isinf(bound2 - bound1))
            {
                /* The quotient is surely in [0,1], so this can't overflow */
                result = count * ((operand - bound1) / (bound2 - bound1));
            }
            else
            {
                /*
                 * We get here if bound2 - bound1 overflows DBL_MAX.  Since
                 * both bounds are finite, their difference can't exceed twice
                 * DBL_MAX; so we can perform the computation without overflow
                 * by dividing all the inputs by 2.  That should be exact too,
                 * except in the case where a very small operand underflows to
                 * zero, which would have negligible impact on the result
                 * given such large bounds.
                 */
                result = count * ((operand / 2 - bound1 / 2) / (bound2 / 2 - bound1 / 2));
            }
            /* The quotient could round to 1.0, which would be a lie */
            if (result >= count)
                result = count - 1;
            /* Having done that, we can add 1 without fear of overflow */
            result++;
        }
    }
    else if (bound1 > bound2)
    {
        if (operand > bound1)
            result = 0;
        else if (operand <= bound2)
        {
            if (pg_add_s32_overflow(count, 1, &result))
                ereport(ERROR,
                        (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                         errmsg("integer out of range")));
        }
        else
        {
            if (!isinf(bound1 - bound2))
                result = count * ((bound1 - operand) / (bound1 - bound2));
            else
                result = count * ((bound1 / 2 - operand / 2) / (bound1 / 2 - bound2 / 2));
            if (result >= count)
                result = count - 1;
            result++;
        }
    }
    else
    {
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
                 errmsg("lower bound cannot equal upper bound")));
        result = 0;             /* keep the compiler quiet */
    }
 
    PG_RETURN_INT32(result);
}