.\" Copyright 2003 Walter Harms, Andries Brouwer
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" Distributed under GPL
.\" %%%LICENSE_END
.\"
.TH FDIM 3 2013-07-15 "" "Linux Programmer's Manual"
.SH NAME
fdim, fdimf, fdiml \- positive difference
.SH SYNOPSIS
.B #include <math.h>
.sp
.BI "double fdim(double " x ", double " y );
.br
.BI "float fdimf(float " x ", float " y );
.br
.BI "long double fdiml(long double " x ", long double " y );
.sp
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR fdimf (),
.BR fdiml ():
.RS 4
_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad
.SH DESCRIPTION
These functions return the positive difference, max(\fIx\fP-\fIy\fP,0),
between their arguments.
.SH RETURN VALUE
On success, these functions return the positive difference.

If
.I x
or
.I y
is a NaN, a NaN is returned.

If the result overflows,
a range error occurs,
and the functions return
.BR HUGE_VAL ,
.BR HUGE_VALF ,
or
.BR HUGE_VALL ,
respectively.
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Range error: result overflow
.\" .I errno
.\" is set to
.\" .BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.PP
These functions do not set
.IR errno .
.\" FIXME . Is it intentional that these functions do not set errno?
.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6796
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
.SS Multithreading (see pthreads(7))
The
.BR fdim (),
.BR fdimf (),
and
.BR fdiml ()
functions are thread-safe.
.SH CONFORMING TO
C99, POSIX.1-2001.
.SH SEE ALSO
.BR fmax (3)
.SH COLOPHON
This page is part of release 3.74 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%http://www.kernel.org/doc/man\-pages/.