Special Quantifies.

Functions to detect and fabricate special quantities in floating-point numbers. More...

Functions
double	trio_nzero (void)
	Generate negative zero. More...
double	trio_pinf (void)
	Generate positive infinity. More...
double	trio_ninf (void)
	Generate negative infinity. More...
double	trio_nan (void)
	Generate NaN. More...
int	trio_isnan (double number)
	Check for NaN. More...
int	trio_isinf (double number)
	Check for infinity. More...
int	trio_isfinite (double number)
	Check for finity. More...
int	trio_signbit (double number)
	Examine the sign of a number. More...
int	trio_fpclassify (double number)
	Examine the class of a number. More...

Detailed Description

Functions to detect and fabricate special quantities in floating-point numbers.

SYNOPSIS

cc ... -ltrio -lm

#include <trionan.h>

DESCRIPTION

Certain arithmetical operations does not result in normal numbers. Instead they result in special quantities that must be handled differently by the floating-point hardware. These includes Infinity and Not-A-Number (NaN).

For example, 0/0 (zero divided by zero) yields NaN. Any operation which involves a NaN will result in NaN. Any comparison involving NaN will be unsuccessful, even if NaN is compared to NaN.

These special quantities are represented with special bit patterns by the floating-point hardware, and this bit patterns depend on the hardware. There may even be hardware that does not support special quantities, so the functions in this module are not guaranteed to work on all platforms.

The approach used in this module is to (in decreasing order of importance)

Use C99 functionality when available.
Use IEEE 754-1985 bit patterns if possible.
Use platform-specific techniques.

NOTES

This module does not depend on the rest of trio, and can thus be reused separately. The following files are necessary:

triodef.h
trionan.h
trionan.c

Function Documentation

int trio_fpclassify ( double number )

Examine the class of a number.

Parameters:

number An arbitrary floating-point number.

Returns:
Enumerable value indicating the class of number

int trio_isfinite ( double number )

Check for finity.

Parameters:

number An arbitrary floating-point number.

Returns:
Boolean value indicating whether or not the number is a finite.

int trio_isinf ( double number )

Check for infinity.

Parameters:

number An arbitrary floating-point number.

Returns:
1 if positive infinity, -1 if negative infinity, 0 otherwise.

int trio_isnan ( double number )

Check for NaN.

Parameters:

number An arbitrary floating-point number.

Returns:
Boolean value indicating whether or not the number is a NaN.

double trio_nan ( void )

Generate NaN.

Returns:
Floating-point representation of NaN.

double trio_ninf ( void )

Generate negative infinity.

Returns:
Floating-point value of negative infinity.

double trio_nzero ( void )

Generate negative zero.

Returns:
Floating-point representation of negative zero.

double trio_pinf ( void )

Generate positive infinity.

Returns:
Floating-point representation of positive infinity.

int trio_signbit ( double number )

Examine the sign of a number.

Parameters:

number An arbitrary floating-point number.

Returns:
Boolean value indicating whether or not the number has the sign bit set (i.e. is negative).