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.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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2008-08-01 05:26:37 +00:00
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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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2004-11-03 13:51:07 +00:00
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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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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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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.\" manual page may be incorrect or out-of-date.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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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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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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.\"
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.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 2002-08-10 Walter Harms
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2004-11-11 17:54:23 +00:00
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.\" (walter.harms@informatik.uni-oldenburg.de)
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2004-11-03 13:51:07 +00:00
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.\" Modified 2003-11-18, 2004-10-05 aeb
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.\"
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_exit.2, brk.2, capget.2, chdir.2, chmod.2, chown.2, chroot.2, getdtablesize.2, gethostname.2, getpagesize.2, getsid.2, killpg.2, mknod.2, mknodat.2, poll.2, posix_fadvise.2, pread.2, readlink.2, setpgid.2, setreuid.2, sigaltstack.2, stat.2, symlink.2, sync.2, truncate.2, vfork.2, wait.2, wait4.2, a64l.3, abs.3, acos.3, acosh.3, asin.3, asinh.3, atan.3, atan2.3, atoi.3, cbrt.3, ceil.3, copysign.3, cosh.3, dirfd.3, div.3, ecvt.3, erf.3, erfc.3, exp.3, exp2.3, fabs.3, fdim.3, ffs.3, floor.3, fma.3, fmax.3, fmin.3, fmod.3, fpclassify.3, frexp.3, ftw.3, fwide.3, gcvt.3, getcwd.3, getdate.3, getgrent.3, gethostid.3, getpass.3, getpwent.3, getsubopt.3, getw.3, hypot.3, ilogb.3, index.3, isalpha.3, isgreater.3, iswblank.3, j0.3, ldexp.3, lockf.3, log.3, log10.3, log1p.3, logb.3, lrint.3, lround.3, mkstemp.3, mktemp.3, modf.3, mq_receive.3, mq_send.3, nan.3, nextafter.3, posix_fallocate.3, posix_memalign.3, printf.3, qecvt.3, random.3, realpath.3, remainder.3, remquo.3, rint.3, round.3, scalb.3, scalbln.3, scanf.3, siginterrupt.3, signbit.3, sigset.3, sinh.3, sqrt.3, strcasecmp.3, strcat.3, strchr.3, strcmp.3, strcoll.3, strcpy.3, strfry.3, strpbrk.3, strsep.3, strspn.3, strstr.3, strtod.3, strtok.3, strtol.3, strtoul.3, strxfrm.3, tanh.3, tgamma.3, trunc.3, ttyslot.3, ualarm.3, usleep.3, wprintf.3, armscii-8.7, cp1251.7, iso_8859-10.7, iso_8859-11.7, iso_8859-13.7, iso_8859-14.7, iso_8859-3.7, iso_8859-5.7, iso_8859-6.7, iso_8859-8.7, koi8-u.7: tstamp
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-09-19 17:19:13 +00:00
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.TH REMAINDER 3 2010-09-20 "" "Linux Programmer's Manual"
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.SH NAME
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drem, dremf, dreml, remainder, remainderf, remainderl \- \
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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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/* The C99 versions */
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.BI "double remainder(double " x ", double " y );
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.BI "float remainderf(float " x ", float " y );
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.BI "long double remainderl(long double " x ", long double " y );
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.sp
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/* Obsolete synonyms */
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.BI "double drem(double " x ", double " y );
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.BI "float dremf(float " x ", float " y );
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.BI "long double dreml(long double " x ", long double " y );
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.sp
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.fi
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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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2007-07-08 12:11:40 +00:00
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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 remainder ():
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2010-09-18 15:09:53 +00:00
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.RS 4
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2010-09-18 15:11:07 +00:00
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_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
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_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED ||
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_ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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.br
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or
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.I cc\ -std=c99
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2010-09-18 15:09:53 +00:00
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.RE
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.br
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.BR remainderf (),
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.BR remainderl ():
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2010-09-18 15:09:53 +00:00
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.RS 4
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2010-09-18 15:11:07 +00:00
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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.br
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or
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.I cc\ -std=c99
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2010-09-18 15:09:53 +00:00
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.RE
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.br
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.BR drem (),
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2007-07-08 12:39:24 +00:00
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.BR dremf (),
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2007-07-08 12:11:40 +00:00
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.BR dreml ():
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2010-09-18 15:09:53 +00:00
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.RS 4
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2007-07-08 12:11:40 +00:00
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_SVID_SOURCE || _BSD_SOURCE
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2010-09-18 15:09:53 +00:00
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.RE
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2007-07-08 12:11:40 +00:00
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.ad b
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.SH DESCRIPTION
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The
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2005-10-19 07:07:02 +00:00
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.BR remainder ()
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function computes the remainder of dividing
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.I x
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by
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.IR y .
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The return value is
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\fIx\fP\-\fIn\fP*\fIy\fP,
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where
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.I n
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is the value
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.IR "x\ /\ y" ,
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rounded to the nearest integer.
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If the absolute value of
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\fIx\fP\-\fIn\fP*\fIy\fP
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is 0.5,
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.I n
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is chosen to be even.
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2008-08-07 11:46:19 +00:00
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These functions are unaffected by the current rounding mode (see
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.BR fenv (3)).
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.LP
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The
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.BR drem ()
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function does precisely the same thing.
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.SH "RETURN VALUE"
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On success, these
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functions return the floating-point remainder,
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\fIx\fP\-\fIn\fP*\fIy\fP.
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If the return value is 0, it has the sign of
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.IR x .
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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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and
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.I y
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is not a NaN,
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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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.\" FIXME . Instead, glibc gives a domain error even if x is a NaN
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and
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.I x
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is not a NaN,
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.\" Interestingly, remquo(3) does not have the same problem.
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a domain error occurs, and
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a NaN is returned.
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2004-11-03 13:51:07 +00:00
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.SH ERRORS
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2008-08-01 05:26:37 +00:00
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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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2008-08-01 05:26:37 +00:00
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Domain error: \fIx\fP is an infinity and \fIy\fP is not a NaN
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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=6783
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.TP
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Domain error: \fIy\fP is zero\" [XXX see bug above] and \fIx\fP is not a NaN
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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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2004-11-03 13:51:07 +00:00
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.SH "CONFORMING TO"
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2008-08-01 05:26:37 +00:00
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.\" IEC 60559.
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2007-04-12 22:42:49 +00:00
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The functions
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.BR remainder (),
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.BR remainderf (),
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and
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2005-10-19 16:30:05 +00:00
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.BR remainderl ()
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2008-08-01 05:26:37 +00:00
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are specified in C99 and POSIX.1-2001.
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2008-06-11 05:58:47 +00:00
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2004-11-03 13:51:07 +00:00
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The function
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.BR drem ()
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2007-04-24 16:44:51 +00:00
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is from 4.3BSD.
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The
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2006-08-04 09:41:28 +00:00
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.I float
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and
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.I "long double"
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variants
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2005-10-19 07:07:02 +00:00
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.BR dremf ()
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2004-11-03 13:51:07 +00:00
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and
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2005-10-19 07:07:02 +00:00
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.BR dreml ()
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2004-11-03 13:51:07 +00:00
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exist on some systems, such as Tru64 and glibc2.
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2008-06-11 05:58:47 +00:00
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Avoid the use of these functions in favor of
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.BR remainder ()
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etc.
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2008-08-01 05:26:37 +00:00
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.SH BUGS
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The call
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remainder(nan(""), 0);
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returns a NaN, as expected, but wrongly causes a domain error;
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it should yield a silent NaN.
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.\" FIXME . this bug occurs as at glibc 2.8.
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.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6779
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2008-08-05 10:28:20 +00:00
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.SH EXAMPLE
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The call "remainder(29.0, 3.0)" returns \-1.
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2004-11-03 13:51:07 +00:00
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.SH "SEE ALSO"
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2009-02-03 03:30:31 +00:00
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.BR div (3),
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2004-11-11 17:54:23 +00:00
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.BR fmod (3),
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.BR remquo (3)
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