fabs(3)			    Library Functions Manual			 fabs(3)

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

LIBRARY
     Math library (libm, -lm)

SYNOPSIS
     #include <math.h>

     double fabs(double x);
     float fabsf(float x);
     long double fabsl(long double x);

 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

     fabsf(), fabsl():
	 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
	     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
	     || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

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 re-
     turned.

ERRORS
     No errors occur.

ATTRIBUTES
     For an explanation of the terms used in this  section,  see  attributes(7).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ fabs(), fabsf(),
     fabsl() T}	  Thread safety	 MT-Safe

STANDARDS
     C11, POSIX.1-2008.

HISTORY
     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)

Linux man-pages 6.18		   2026-02-08				 fabs(3)