fabs(), fabsf(), fabsl()

Compute the absolute value of a double number

Synopsis:

#include <math.h>

double fabs( double x );

float fabsf( float x );

long double fabsl( long double x );

libm: The general-purpose math library.
libm-sve: (QNX Neutrino 7.1 or later) 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.

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

The fabs(), fabsf(), and fabsl() functions compute the absolute value of x.

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

Call feclearexcept(FE_ALL_EXCEPT) before calling fabs(), fabsf(), or fabsl().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

The absolute value of x.

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

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

int main( void )
{
    printf( "%f %f\n", fabs(.5), fabs(-.5) );
    return EXIT_SUCCESS;
}

produces the output:

0.500000 0.500000