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(x)
double x;

int isnan(x)
double x;

double copysign(x,y)
double x, y;

double scalbn(x,n)
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(x) corresponds to the IEEE’s class() and classifies x as zero, subnormal, normal, ∞, or quiet or signaling NaN; /usr/ucbinclude/sys/ieeefp.h defines enum fp_class_type.  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

  —  BSD Compatibility Package