float.c

PostgreSQL7.4.6 for Linux

/*-------------------------------------------------------------------------
 *
 * float.c
 *	  Functions for the built-in floating-point types.
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/float.c,v 1.94 2003/09/25 06:58:03 petere Exp $
 *
 *-------------------------------------------------------------------------
 */
/*----------
 * OLD COMMENTS
 *		Basic float4 ops:
 *		 float4in, float4out, float4recv, float4send
 *		 float4abs, float4um, float4up
 *		Basic float8 ops:
 *		 float8in, float8out, float8recv, float8send
 *		 float8abs, float8um, float8up
 *		Arithmetic operators:
 *		 float4pl, float4mi, float4mul, float4div
 *		 float8pl, float8mi, float8mul, float8div
 *		Comparison operators:
 *		 float4eq, float4ne, float4lt, float4le, float4gt, float4ge, float4cmp
 *		 float8eq, float8ne, float8lt, float8le, float8gt, float8ge, float8cmp
 *		Conversion routines:
 *		 ftod, dtof, i4tod, dtoi4, i2tod, dtoi2, itof, ftoi, i2tof, ftoi2
 *
 *		Random float8 ops:
 *		 dround, dtrunc, dsqrt, dcbrt, dpow, dexp, dlog1
 *		Arithmetic operators:
 *		 float48pl, float48mi, float48mul, float48div
 *		 float84pl, float84mi, float84mul, float84div
 *		Comparison operators:
 *		 float48eq, float48ne, float48lt, float48le, float48gt, float48ge
 *		 float84eq, float84ne, float84lt, float84le, float84gt, float84ge
 *
 *		(You can do the arithmetic and comparison stuff using conversion
 *		 routines, but then you pay the overhead of invoking a separate
 *		 conversion function...)
 *
 * XXX GLUESOME STUFF. FIX IT! -AY '94
 *
 *		Added some additional conversion routines and cleaned up
 *		 a bit of the existing code. Need to change the error checking
 *		 for calls to pow(), exp() since on some machines (my Linux box
 *		 included) these routines do not set errno. - tgl 97/05/10
 *----------
 */
#include "postgres.h"

#include <ctype.h>
#include <errno.h>
#include <float.h>				/* faked on sunos4 */
#include <math.h>

#include <limits.h>
/* for finite() on Solaris */
#ifdef HAVE_IEEEFP_H
#include <ieeefp.h>
#endif

#include "catalog/pg_type.h"
#include "fmgr.h"
#include "libpq/pqformat.h"
#include "utils/array.h"
#include "utils/builtins.h"


#ifndef HAVE_CBRT
static double cbrt(double x);
#endif   /* HAVE_CBRT */

#ifndef M_PI
/* from my RH5.2 gcc math.h file - thomas 2000-04-03 */
#define M_PI 3.14159265358979323846
#endif

#ifndef NAN
#define NAN		(0.0/0.0)
#endif

#ifndef SHRT_MAX
#define SHRT_MAX 32767
#endif
#ifndef SHRT_MIN
#define SHRT_MIN (-32768)
#endif

/* not sure what the following should be, but better to make it over-sufficient */
#define MAXFLOATWIDTH	64
#define MAXDOUBLEWIDTH	128

/* ========== USER I/O ROUTINES ========== */


#define FLOAT4_MAX		 FLT_MAX
#define FLOAT4_MIN		 FLT_MIN
#define FLOAT8_MAX		 DBL_MAX
#define FLOAT8_MIN		 DBL_MIN


/* Configurable GUC parameter */
int			extra_float_digits = 0;		/* Added to DBL_DIG or FLT_DIG */


static void CheckFloat4Val(double val);
static void CheckFloat8Val(double val);
static int	float4_cmp_internal(float4 a, float4 b);
static int	float8_cmp_internal(float8 a, float8 b);


/*
 * check to see if a float4 val is outside of
 * the FLOAT4_MIN, FLOAT4_MAX bounds.
 *
 * raise an ereport warning if it is
*/
static void
CheckFloat4Val(double val)
{
	/*
	 * defining unsafe floats's will make float4 and float8 ops faster at
	 * the cost of safety, of course!
	 */
#ifdef UNSAFE_FLOATS
	return;
#else
	if (fabs(val) > FLOAT4_MAX)
		ereport(ERROR,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("type \"real\" value out of range: overflow")));
	if (val != 0.0 && fabs(val) < FLOAT4_MIN)
		ereport(ERROR,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("type \"real\" value out of range: underflow")));

	return;
#endif   /* UNSAFE_FLOATS */
}

/*
 * check to see if a float8 val is outside of
 * the FLOAT8_MIN, FLOAT8_MAX bounds.
 *
 * raise an ereport error if it is
 */
static void
CheckFloat8Val(double val)
{
	/*
	 * defining unsafe floats's will make float4 and float8 ops faster at
	 * the cost of safety, of course!
	 */
#ifdef UNSAFE_FLOATS
	return;
#else
	if (fabs(val) > FLOAT8_MAX)
		ereport(ERROR,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("type \"double precision\" value out of range: overflow")));
	if (val != 0.0 && fabs(val) < FLOAT8_MIN)
		ereport(ERROR,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("type \"double precision\" value out of range: underflow")));
#endif   /* UNSAFE_FLOATS */
}

/*
 *		float4in		- converts "num" to float
 *						  restricted syntax:
 *						  {<sp>} [+|-] {digit} [.{digit}] [<exp>]
 *						  where <sp> is a space, digit is 0-9,
 *						  <exp> is "e" or "E" followed by an integer.
 */
Datum
float4in(PG_FUNCTION_ARGS)
{
	char	   *num = PG_GETARG_CSTRING(0);
	double		val;
	char	   *endptr;

	errno = 0;
	val = strtod(num, &endptr);
	if (*endptr != '\0')
	{
		/*
		 * XXX we should accept "Infinity" and "-Infinity" too, but what
		 * are the correct values to assign?  HUGE_VAL will provoke an
		 * error from CheckFloat4Val.
		 */
		if (strcasecmp(num, "NaN") == 0)
			val = NAN;
		else
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type real: \"%s\"",
							num)));
	}
	else
	{
		if (errno == ERANGE)
			ereport(ERROR,
					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
					 errmsg("\"%s\" is out of range for type real", num)));
	}

	/*
	 * if we get here, we have a legal double, still need to check to see
	 * if it's a legal float
	 */
	CheckFloat4Val(val);

	PG_RETURN_FLOAT4((float4) 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(MAXFLOATWIDTH + 1);
	int			infflag;
	int			ndig;

	if (isnan(num))
		PG_RETURN_CSTRING(strcpy(ascii, "NaN"));
	infflag = isinf(num);
	if (infflag > 0)
		PG_RETURN_CSTRING(strcpy(ascii, "Infinity"));
	if (infflag < 0)
		PG_RETURN_CSTRING(strcpy(ascii, "-Infinity"));

	ndig = FLT_DIG + extra_float_digits;
	if (ndig < 1)
		ndig = 1;

	sprintf(ascii, "%.*g", 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
 *						  restricted syntax:
 *						  {<sp>} [+|-] {digit} [.{digit}] [<exp>]
 *						  where <sp> is a space, digit is 0-9,
 *						  <exp> is "e" or "E" followed by an integer.
 */
Datum
float8in(PG_FUNCTION_ARGS)
{
	char	   *num = PG_GETARG_CSTRING(0);
	double		val;
	char	   *endptr;

	errno = 0;
	val = strtod(num, &endptr);
	if (*endptr != '\0')
	{
		if (strcasecmp(num, "NaN") == 0)
			val = NAN;
		else if (strcasecmp(num, "Infinity") == 0)
			val = HUGE_VAL;
		else if (strcasecmp(num, "-Infinity") == 0)
			val = -HUGE_VAL;
		else
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type double precision: \"%s\"",
							num)));
	}
	else
	{
		if (errno == ERANGE)
			ereport(ERROR,
					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
					 errmsg("\"%s\" is out of range for type double precision", num)));
	}

	CheckFloat8Val(val);

	PG_RETURN_FLOAT8(val);
}

/*
 *		float8out		- converts float8 number to a string
 *						  using a standard output format
 */
Datum
float8out(PG_FUNCTION_ARGS)
{
	float8		num = PG_GETARG_FLOAT8(0);
	char	   *ascii = (char *) palloc(MAXDOUBLEWIDTH + 1);
	int			infflag;
	int			ndig;

	if (isnan(num))
		PG_RETURN_CSTRING(strcpy(ascii, "NaN"));
	infflag = isinf(num);
	if (infflag > 0)
		PG_RETURN_CSTRING(strcpy(ascii, "Infinity"));
	if (infflag < 0)
		PG_RETURN_CSTRING(strcpy(ascii, "-Infinity"));

	ndig = DBL_DIG + extra_float_digits;
	if (ndig < 1)
		ndig = 1;

	sprintf(ascii, "%.*g", ndig, num);

	PG_RETURN_CSTRING(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((float4) fabs(arg1));
}

/*
 *		float4um		- returns -arg1 (unary minus)
 */
Datum
float4um(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);

	PG_RETURN_FLOAT4((float4) -arg1);
}

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_cmp_internal(arg1, arg2) > 0)
		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_cmp_internal(arg1, arg2) < 0)
		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);
	float8		result;

	result = fabs(arg1);

	CheckFloat8Val(result);
	PG_RETURN_FLOAT8(result);
}


/*
 *		float8um		- returns -arg1 (unary minus)
 */
Datum
float8um(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		result;

	result = ((arg1 != 0) ? -(arg1) : arg1);

	CheckFloat8Val(result);
	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_cmp_internal(arg1, arg2) > 0)
		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_cmp_internal(arg1, arg2) < 0)
		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);
	double		result;

	result = arg1 + arg2;
	CheckFloat4Val(result);
	PG_RETURN_FLOAT4((float4) result);
}

Datum
float4mi(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		arg2 = PG_GETARG_FLOAT4(1);
	double		result;

	result = arg1 - arg2;
	CheckFloat4Val(result);
	PG_RETURN_FLOAT4((float4) result);
}

Datum
float4mul(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		arg2 = PG_GETARG_FLOAT4(1);
	double		result;

	result = arg1 * arg2;
	CheckFloat4Val(result);
	PG_RETURN_FLOAT4((float4) result);
}

Datum
float4div(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		arg2 = PG_GETARG_FLOAT4(1);
	double		result;

	if (arg2 == 0.0)
		ereport(ERROR,
				(errcode(ERRCODE_DIVISION_BY_ZERO),
				 errmsg("division by zero")));

	/* Do division in float8, then check for overflow */
	result = (float8) arg1 / (float8) arg2;

	CheckFloat4Val(result);
	PG_RETURN_FLOAT4((float4) result);
}

/*
 *		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);
	float8		result;

	result = arg1 + arg2;

	CheckFloat8Val(result);
	PG_RETURN_FLOAT8(result);
}

Datum
float8mi(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		arg2 = PG_GETARG_FLOAT8(1);
	float8		result;

	result = arg1 - arg2;

	CheckFloat8Val(result);
	PG_RETURN_FLOAT8(result);
}

Datum
float8mul(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		arg2 = PG_GETARG_FLOAT8(1);
	float8		result;

	result = arg1 * arg2;

	CheckFloat8Val(result);
	PG_RETURN_FLOAT8(result);
}

Datum
float8div(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		arg2 = PG_GETARG_FLOAT8(1);
	float8		result;

	if (arg2 == 0.0)
		ereport(ERROR,
				(errcode(ERRCODE_DIVISION_BY_ZERO),
				 errmsg("division by zero")));

	result = arg1 / arg2;

	CheckFloat8Val(result);
	PG_RETURN_FLOAT8(result);
}


/*
 *		====================
 *		COMPARISON OPERATORS
 *		====================
 */

/*
 *		float4{eq,ne,lt,le,gt,ge}		- float4/float4 comparison operations
 */
static int
float4_cmp_internal(float4 a, float4 b)
{
	/*
	 * We consider all NANs to be equal and larger than any non-NAN. This
	 * is somewhat arbitrary; the important thing is to have a consistent
	 * sort order.
	 */
	if (isnan(a))
	{
		if (isnan(b))
			return 0;			/* NAN = NAN */
		else
			return 1;			/* NAN > non-NAN */
	}
	else if (isnan(b))
	{
		return -1;				/* non-NAN < NAN */
	}
	else
	{
		if (a > b)
			return 1;
		else if (a < b)
			return -1;
		else
			return 0;
	}
}

Datum
float4eq(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		arg2 = PG_GETARG_FLOAT4(1);