The Open Group Base Specifications Issue 7

IEEE Std 1003.1-2008, 2016 Edition

Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

copysign, copysignf, copysignl - number manipulation function

#### SYNOPSIS

`#include <math.h>`

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

float copysignf(float *x*`, float` *y*`);`

long double copysignl(long double *x*`, long double` *y*`);`

#### DESCRIPTION

^{[CX]} The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C
standard.

These functions shall produce a value with the magnitude of *x* and the sign of *y*. On implementations that represent
a signed zero but do not treat negative zero consistently in arithmetic operations, these functions regard the sign of zero as
positive.

#### RETURN VALUE

Upon successful completion, these functions shall return a value with the magnitude of *x* and the sign of *y*.

#### ERRORS

No errors are defined.

*The following sections are informative.*

#### EXAMPLES

None.

#### APPLICATION USAGE

None.

#### RATIONALE

None.

#### FUTURE DIRECTIONS

None.

#### SEE ALSO

*signbit*

XBD *<math.h>*

#### CHANGE HISTORY

First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.

*End of informative text.*

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