.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" 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 (faith@cs.unc.edu)
.\" Added fabsl, fabsf, aeb, 2001-06-07
.\"
.TH FABS 3  2021-03-22 "" "Linux Programmer's Manual"
.SH NAME
fabs, fabsf, fabsl \- absolute value of floating-point number
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double fabs(double " x );
.BI "float fabsf(float " x );
.BI "long double fabsl(long double " x );
.fi
.PP
Link with \fI\-lm\fP.
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR fabsf (),
.BR fabsl ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.SH DESCRIPTION
These functions return the absolute value of the floating-point
number
.IR x .
.SH RETURN VALUE
These functions return the absolute value of
.IR x .
.PP
If
.I x
is a NaN, a NaN is returned.
.PP
If
.I x
is \-0, +0 is returned.
.PP
If
.I x
is negative infinity or positive infinity, positive infinity is returned.
.SH ERRORS
No errors occur.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR fabs (),
.BR fabsf (),
.BR fabsl ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.PP
The variant returning
.I double
also conforms to
SVr4, 4.3BSD, C89.
.SH SEE ALSO
.BR abs (3),
.BR cabs (3),
.BR ceil (3),
.BR floor (3),
.BR labs (3),
.BR rint (3)