.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)

.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk

.\"     <mtk.manpages@gmail.com>

.\"

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.\"

.\" References consulted:

.\"     Linux libc source code

.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)

.\"     386BSD man pages

.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)

.\" Modified 2002-07-27 by Walter Harms

.\" 	(walter.harms@informatik.uni-oldenburg.de)

.\"

.TH FMOD 3  2017-09-15 "" "Linux Programmer's Manual"

.SH NAME

fmod, fmodf, fmodl \- floating-point remainder function

.SH SYNOPSIS

.nf

.B #include <math.h>

.PP

.BI "double fmod(double " x ", double " y );

.BI "float fmodf(float " x ", float " y );

.BI "long double fmodl(long double " x ", long double " y );

.fi

.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 fmodf (),

.BR fmodl ():

.RS 4

_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L

    || /* Since glibc 2.19: */ _DEFAULT_SOURCE

    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

.RE

.ad

.SH DESCRIPTION

These functions compute the floating-point remainder of dividing

.I x

by

.IR y .

The return value is

.IR x

\-

.I n

*

.IR y ,

where

.I n

is the quotient of

.I x

/

.IR y ,

rounded toward zero to an integer.

.SH RETURN VALUE

On success, these

functions return the value \fIx\fP\ \-\ \fIn\fP*\fIy\fP,

for some integer

.IR n ,

such that the returned value has the same sign as

.I x

and a magnitude less than the magnitude of

.IR y .

.PP

If

.I x

or

.I y

is a NaN, a NaN is returned.

.PP

If

.I x

is an infinity,

a domain error occurs, and

a NaN is returned.

.PP

If

.I y

is zero,

a domain error occurs, and

a NaN is returned.

.PP

If

.I x

is +0 (\-0), and

.I y

is not zero, +0 (\-0) is returned.

.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

Domain error: \fIx\fP is an infinity

.I errno

is set to

.BR EDOM

(but see BUGS).

An invalid floating-point exception

.RB ( FE_INVALID )

is raised.

.TP

Domain error: \fIy\fP is zero

.I errno

is set to

.BR EDOM .

An invalid floating-point exception

.RB ( FE_INVALID )

is raised.

.\" POSIX.1 documents an optional underflow error, but AFAICT it doesn't

.\" (can't?) occur -- mtk, Jul 2008

.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 fmod (),

.BR fmodf (),

.BR fmodl ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

.PP

The variant returning

.I double

also conforms to

SVr4, 4.3BSD, C89.

.SH BUGS

Before version 2.10, the glibc implementation did not set

.\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6784

.I errno

to

.B EDOM

when a domain error occurred for an infinite

.IR x .

.SH SEE ALSO

.BR remainder (3)

.SH COLOPHON

This page is part of release 4.15 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

\%https://www.kernel.org/doc/man\-pages/.