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man pages->NetBSD man pages -> copysign (3)
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## IEEE(3)

### NAME[Toc][Back]

copysign, copysignf, finite, finitef, ilogb, ilogbf, nextafter,
nextafterf, remainder, remainderf, scalbn, scalbnf - Functions for IEEE
arithmetic

### LIBRARY[Toc][Back]

Math Library (libm, -lm)

### SYNOPSIS[Toc][Back]

#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[Toc][Back]

These functions are required or recommended by IEEE Std 754-1985.

copysign() returns x with its sign changed to y's.

finite() returns the value 1 just when -infinity < x < +infinity; otherwise
a zero is returned (when |x| = infinity or x is NaN).

ilogb() returns x's exponent n, in integer format.  ilogb(+-infinity)
returns INT_MAX and ilogb(0) returns INT_MIN.

nextafter() returns the next machine representable number from x in
direction 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.

math(3)

### STANDARDS[Toc][Back]

IEEE Std 754-1985

### HISTORY[Toc][Back]

The ieee functions appeared in 4.3BSD.

BSD                            February 25, 1994                           BSD
[ Back ]
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