Linux manual pages Section 3: Subroutines  

Name

fabs, fabsf, fabsl — absolute value of floating-point number

Synopsis

#include <math.h>
double fabs( double x);
 
float fabsf( float x);
 
long double fabsl( long double x);
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
fabsf(), fabsl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
[Note] Note

Link with −lm.

DESCRIPTION

These functions return the absolute value of the floating-point number x.

RETURN VALUE

These functions return the absolute value of x.

If x is a NaN, a NaN is returned.

If x is −0, +0 is returned.

If x is negative infinity or positive infinity, positive infinity is returned.

ERRORS

No errors occur.

ATTRIBUTES

Multithreading (see pthreads(7))

The fabs(), fabsf(), and fabsl() functions are thread-safe.

CONFORMING TO

C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO

abs(3), cabs(3), ceil(3), floor(3), labs(3), rint(3)

COLOPHON

This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright 1993 David Metcalfe (davidprism.demon.co.uk)

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References consulted:
    Linux libc source code
    Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
    386BSD man pages
Modified Sat Jul 24 19:42:04 1993 by Rik Faith (faithcs.unc.edu)
Added fabsl, fabsf, aeb, 2001-06-07