.\" Copyright 2003 Walter Harms, Andries Brouwer
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\" Distributed under GPL.
.\"
.TH FDIM 3 2008-08-11 "" "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 ():
_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
.I cc\ -std=c99
.ad b
.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 "CONFORMING TO"
C99, POSIX.1-2001.
.SH "SEE ALSO"
.BR fmax (3)
.SH COLOPHON
This page is part of release 3.22 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
