ieee(3)
- NetBSD Manual Pages
IEEE(3) NetBSD Programmer's Manual IEEE(3)
NAME
copysign, finite, ilogb, nextafter, remainder, scalbn - Functions for
IEEE arithmetic
LIBRARY
Math Library (libm, -lm)
SYNOPSIS
#include <math.h>
double
copysign(double x, double y);
float
copysignf(float x, float y);
int
finite(double x);
int
finitef(float x);
int
ilogb(double x);
int
ilogbf(float x);
double
nextafter(double x, double y);
float
nextafterf(float x, float y);
double
remainder(double x, double y);
float
remainderf(float x, float y);
double
scalbn(double x, int n);
float
scalbnf(float x, int n);
DESCRIPTION
These functions are required or recommended by IEEE Std754-1985.
copysign() returns x with its sign changed to y's.
finite() returns the value 1 just when -infinity < x < +infinity; other-
wise a zero is returned (when |x| = infinity or x is NaN
ilogb() returns x's exponent n, in integer format. ilogb(+-infinity) re-
turns INT_MAX and ilogb(0) returns INT_MIN.
nextafter() returns the next machine representable number from x in di-
rection y.
remainder() returns the remainder r := x - n*y where n is the integer
nearest the exact value of x/y; moreover if |n - x/y| = 1/2 then n is
even. Consequently the remainder is computed exactly and |r| <= |y|/2.
But remainder(x, 0) and remainder(infinity, 0) are invalid operations
that produce a NaN.
scalbn() returns x*(2**n) computed by exponent manipulation.
SEE ALSO
math(3)
HISTORY
The ieee functions appeared in 4.3BSD.
STANDARDS
IEEE Std754-1985
NetBSD 1.4 Feb 25, 1994 2
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