copysign(), copysignf(), copysignl()

Arguments:

x

The number to use the magnitude of.

y

The number to use the sign of.

Library:

libm

The general-purpose math library.

libm-sve

A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

• If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
• If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.

Description:

The copysign(), copysignf(), and copysignl() functions return the magnitude of x with the sign bit of y.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

• Call feclearexcept(FE_ALL_EXCEPT) before calling copysign(), copysignf(), or copysignl().
• On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

The magnitude of x with the sign bit of y.

Examples:

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

int main(int argc, char** argv) 
{
   double a, b, c;

   a = 27.0;
   b = -5;
   c = copysign(a, b);
   printf("The magnitude of %f and sign of %f gives %f\n",
          a, b, c);

   return(EXIT_SUCCESS);
}

produces the output:

The magnitude of 27.000000 and sign of -5.000000 gives -27.000000

Classification:

C11, POSIX 1003.1