.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\" <mtk.manpages@gmail.com>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" References consulted:
.\" Linux libc source code
.\" (walter.harms@informatik.uni-oldenburg.de)
.\" Modified 2003-11-18, 2004-10-05 aeb
.\"
-.TH REMAINDER 3 2008-08-05 "" "Linux Programmer's Manual"
+.TH REMAINDER 3 2017-09-15 "" "Linux Programmer's Manual"
.SH NAME
drem, dremf, dreml, remainder, remainderf, remainderl \- \
floating-point remainder function
.SH SYNOPSIS
.nf
.B #include <math.h>
-.sp
+.PP
/* The C99 versions */
.BI "double remainder(double " x ", double " y );
.BI "float remainderf(float " x ", float " y );
.BI "long double remainderl(long double " x ", long double " y );
-.sp
+.PP
/* Obsolete synonyms */
.BI "double drem(double " x ", double " y );
.BI "float dremf(float " x ", float " y );
.BI "long double dreml(long double " x ", long double " y );
-.sp
+.PP
.fi
Link with \fI\-lm\fP.
-.sp
+.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
-.sp
+.PP
.ad l
.BR remainder ():
-_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
-.I cc\ -std=c99
+.RS 4
+_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
+ || _XOPEN_SOURCE\ >=\ 500
+.\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
+ || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+ || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.RE
.br
.BR remainderf (),
.BR remainderl ():
-_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
-.I cc\ -std=c99
+.RS 4
+_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
+ || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+ || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.RE
.br
.BR drem (),
.BR dremf (),
.BR dreml ():
-_SVID_SOURCE || _BSD_SOURCE
+.RS 4
+/* Since glibc 2.19: */ _DEFAULT_SOURCE
+ || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.RE
.ad b
.SH DESCRIPTION
-The
-.BR remainder ()
-function computes the remainder of dividing
+These
+functions compute the remainder of dividing
.I x
by
.IR y .
is the value
.IR "x\ /\ y" ,
rounded to the nearest integer.
-If the absolute value of
+If the absolute value of
\fIx\fP\-\fIn\fP*\fIy\fP
is 0.5,
.I n
is chosen to be even.
-
-These functions are unaffected by the current rounding mode.
-.LP
+.PP
+These functions are unaffected by the current rounding mode (see
+.BR fenv (3)).
+.PP
The
.BR drem ()
function does precisely the same thing.
-.SH "RETURN VALUE"
+.SH RETURN VALUE
On success, these
functions return the floating-point remainder,
\fIx\fP\-\fIn\fP*\fIy\fP.
If the return value is 0, it has the sign of
.IR x .
-
+.PP
If
.I x
or
.I y
is a NaN, a NaN is returned.
-
+.PP
If
.I x
-is an infinity,
+is an infinity,
and
.I y
is not a NaN,
-a "domain error" occurs, and
+a domain error occurs, and
a NaN is returned.
-
+.PP
If
.I y
is zero,
.I x
is not a NaN,
.\" Interestingly, remquo(3) does not have the same problem.
-a "domain error" occurs, and
+a domain error occurs, and
a NaN is returned.
.SH ERRORS
See
The following errors can occur:
.TP
Domain error: \fIx\fP is an infinity and \fIy\fP is not a NaN
-.\" .I errno
-.\" is set to
-.\" .BR EDOM .
+.I errno
+is set to
+.BR EDOM
+(but see BUGS).
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
These functions do not set
.IR errno
for this case.
-.\" FIXME . Is it intentional that these functions do not set errno?
-.\" They do set errno for the y == 0 case, below.
-.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6783
.TP
Domain error: \fIy\fP is zero\" [XXX see bug above] and \fIx\fP is not a NaN
.I errno
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
-.SH "CONFORMING TO"
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbw26 lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR drem (),
+.BR dremf (),
+.BR dreml (),
+.br
+.BR remainder (),
+.BR remainderf (),
+.br
+.BR remainderl ()
+T} Thread safety MT-Safe
+.TE
+.SH CONFORMING TO
.\" IEC 60559.
The functions
.BR remainder (),
.BR remainderf (),
and
.BR remainderl ()
-are specified in C99 and POSIX.1-2001.
-
+are specified in C99, POSIX.1-2001, and POSIX.1-2008.
+.PP
The function
.BR drem ()
is from 4.3BSD.
Avoid the use of these functions in favor of
.BR remainder ()
etc.
-.SH EXAMPLE
-The call "remainder(29.0, 3.0)" returns \-1.
.SH BUGS
-The call
-
+Before glibc 2.15,
+.\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6779
+the call
+.PP
remainder(nan(""), 0);
-
-returns a NaN, as expected, but wrongly causes a domain error;
-it should yield a silent NaN.
-.\" FIXME . this bug occurs as at glibc 2.8.
-.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6779
-.SH "SEE ALSO"
+.PP
+returned a NaN, as expected, but wrongly caused a domain error.
+Since glibc 2.15, a silent NaN (i.e., no domain error) is returned.
+.PP
+Before glibc 2.15,
+.\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6783
+.I errno
+was not set to
+.BR EDOM
+for the domain error that occurs when
+.I x
+is an infinity and
+.I y
+is not a NaN.
+.SH EXAMPLE
+The call "remainder(29.0, 3.0)" returns \-1.
+.SH SEE ALSO
+.BR div (3),
.BR fmod (3),
.BR remquo (3)
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