'\" t
.\" Copyright 2003 Walter Harms, Andries Brouwer
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: GPL-1.0-or-later
.\"
.TH fdim 3 2023-03-30 "Linux man-pages 6.04"
.SH NAME
fdim, fdimf, fdiml \- positive difference
.SH LIBRARY
Math library
.RI ( libm ", " \-lm )
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double fdim(double " x ", double " y );
.BI "float fdimf(float " x ", float " y );
.BI "long double fdiml(long double " x ", long double " y );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR fdimf (),
.BR fdiml ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
.fi
.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.
.PP
If
.I x
or
.I y
is a NaN, a NaN is returned.
.PP
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.
.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 fdim (),
.BR fdimf (),
.BR fdiml ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
glibc 2.1.
C99, POSIX.1-2001.
.SH BUGS
Before glibc 2.24
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6796
on certain architectures (e.g., x86, but not x86_64)
these functions did not set
.IR errno .
.SH SEE ALSO
.BR fmax (3)