man3/fdim.3

.\" 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 2017-09-15 "" "Linux Programmer's Manual"
.SH NAME
fdim, fdimf, fdiml \- positive difference
.SH SYNOPSIS
.B #include <math.h>
.PP
.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 );
.PP
Link with \fI\-lm\fP.
.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.PP
.ad l
.BR fdimf (),
.BR fdiml ():
.RS 4
_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
.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.
.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.
.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
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw24 lb lb
l l l.
Interface	Attribute	Value
T{
.BR fdim (),
.BR fdimf (),
.BR fdiml ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.SH SEE ALSO
.BR fmax (3)