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.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 2002-07-27 by Walter Harms
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.\" (walter.harms@informatik.uni-oldenburg.de)
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.\"
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.TH FMOD 3 2008-07-29 "" "Linux Programmer's Manual"
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.SH NAME
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fmod, fmodf, fmodl \- floating-point remainder function
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.SH SYNOPSIS
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.nf
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.B #include <math.h>
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.sp
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.BI "double fmod(double " x ", double " y );
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.br
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.BI "float fmodf(float " x ", float " y );
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.br
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.BI "long double fmodl(long double " x ", long double " y );
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.fi
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.sp
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2007-07-21 05:25:03 +00:00
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Link with \fI\-lm\fP.
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR fmodf (),
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.BR fmodl ():
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.ad b
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.SH DESCRIPTION
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The
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.BR fmod ()
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function computes the floating-point remainder of dividing \fIx\fP by
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\fIy\fP.
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The return value is \fIx\fP \- \fIn\fP * \fIy\fP, where \fIn\fP
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is the quotient of \fIx\fP / \fIy\fP, rounded towards zero to an integer.
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.SH "RETURN VALUE"
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On success, these
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functions return the value \fIx\fP\ \-\ \fIn\fP*\fIy\fP,
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for some integer \fIn\fP,
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such that the returned value has the same sign as
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.I x
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and a magnitude less than the magnitude of
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.IR y .
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If
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.I x
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or
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.I y
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is a NaN, a NaN is returned.
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If
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.I x
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is an infinity,
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a "domain error" occurs, and
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a NaN is returned.
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If
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.I y
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is zero,
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a "domain error" occurs, and
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a NaN is returned.
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If
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.I x
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is +0 (\-0), and
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.I y
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is not zero, +0 (\-0) is returned.
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.SH ERRORS
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See
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.BR math_error (7)
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for information on how to determine whether an error has occurred
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when calling these functions.
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.PP
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The following errors can occur:
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.TP
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Domain error: \fIx\fP is an infinity
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.\" .I errno
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.\" is set to
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.\" .BR EDOM .
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An invalid floating-point exception
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.RB ( FE_INVALID )
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is raised.
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.IP
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These functions do not set
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.IR errno
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for this case.
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.\" FIXME . Is it intentional that these functions do not set errno?
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.\" They do set errno for the y == 0 case, below.
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.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6784
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.TP
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Domain error: \fIy\fP is zero
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.I errno
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is set to
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.BR EDOM .
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An invalid floating-point exception
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.RB ( FE_INVALID )
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is raised.
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.\" POSIX.1 documents an optional underflow error, but AFAICT it doesn't
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.\" (can't?) occur -- mtk, Jul 2008
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.SH "CONFORMING TO"
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C99, POSIX.1-2001.
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The variant returning
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.I double
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also conforms to
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2006-08-03 13:57:30 +00:00
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SVr4, 4.3BSD, C89.
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.SH "SEE ALSO"
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.BR remainder (3)
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