NAME

ieee_functions, fp_class, isnan, copysign, scalbn − miscellaneous functions for IEEE arithmetic

SYNOPSIS

/usr/ucb/cc [ flag ... ] file ...

#include <fp.h>
#include <math.h>
#include <stdio.h>

enum fp_class_type fp_class(double x);

int isnan(double x);

double copysign(double x, double y);

double scalbn(double x, int n);

DESCRIPTION

Most of these functions provide capabilities required by ANSI/IEEE Std 754-1985 or suggested in its appendix. 

fp_class() corresponds to the IEEE’s class() and classifies x as zero, subnormal, normal, ∞, or quiet, or signaling NaN; <ieeefp.h> defines enum fp_class_type. 

RETURN VALUES

The following function returns 0 if the indicated condition is not satisfied:

isnan(x) returns 1 if x is NaN

copysign(x,y) returns x with y’s sign bit.

scalbn(x,n) returns x∗ 2∗∗n computed by exponent manipulation rather than by actually performing an exponentiation or a multiplication.  Thus

1 ≤ scalbn(fabs(x),−ilogb(x)) < 2
for every x except 0, ∞, and NaN. 

FILES

/usr/ucbinclude/sys/ieeefp.h

/usr/ucbinclude/math.h

/usr/include/values.h

SEE ALSO

floatingpoint(3B)

SunOS 5.1/SPARC  —  Last change: 5 Jul 1990