.\"	$OpenBSD: remainder.3,v 1.8 2016/04/26 19:49:22 tb Exp $
.\"
.\" Copyright (c) 1985, 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     from: @(#)ieee.3	6.4 (Berkeley) 5/6/91
.\" $FreeBSD: src/lib/msun/man/remainder.3,v 1.6 2008/03/30 20:48:02 das Exp $
.\"
.Dd $Mdocdate: April 26 2016 $
.Dt REMAINDER 3
.Os
.Sh NAME
.Nm remainder ,
.Nm remainderf ,
.Nm remainderl ,
.Nm remquo ,
.Nm remquof ,
.Nm remquol ,
.Nm drem ,
.Nm dremf
.Nd minimal residue functions
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn remainder "double x" "double y"
.Ft float
.Fn remainderf "float x" "float y"
.Ft long double
.Fn remainderl "long double x" "long double y"
.Ft double
.Fn remquo "double x" "double y" "int *quo"
.Ft float
.Fn remquof "float x" "float y" "int *quo"
.Ft long double
.Fn remquol "long double x" "long double y" "int *quo"
.Sh DESCRIPTION
.Fn remainder ,
.Fn remainderf ,
.Fn remainderl ,
.Fn remquo ,
.Fn remquof ,
and
.Fn remquol
return the remainder
.Fa r No := Fa x No \(mi Fa n Ns * Ns Fa y
where
.Fa n
is the integer nearest the exact value of
.Bk -words
.Fa x Ns / Ns Fa y ;
.Ek
moreover if
.Eo | Fa n No \(mi Fa x Ns / Ns Fa y Ec | = 1/2
then
.Fa n
is even.
Consequently
the remainder is computed exactly and
.Eo | Fa r Ec | \(<= Eo | Fa y Ec | Ns /2 .
But attempting to take the remainder when
.Fa y
is 0 or
.Fa x
is \(+-infinity is an invalid operation that produces a NaN.
.Pp
The
.Fn remquo ,
.Fn remquof
and
.Fn remquol
functions also store the last
.Va k
bits of
.Fa n
in the location pointed to by
.Fa quo ,
provided that
.Fa n
exists.
The number of bits
.Va k
is platform-specific, but is guaranteed to be at least 3.
.Sh SEE ALSO
.Xr fmod 3 ,
.Xr nextafter 3
.Sh STANDARDS
The
.Fn remainder ,
.Fn remainderf ,
.Fn remainderl ,
.Fn remquo ,
.Fn remquof ,
and
.Fn remquol
routines conform to
.St -isoC-99 .
The remainder is as defined in
.St -ieee754 .
.Pp
.Fn drem
and
.Fn dremf
are deprecated aliases for
.Fn remainder
and
.Fn remainderf ,
respectively.
.Sh HISTORY
The
.Fn remainder
and
.Fn remainderf
functions appeared in
.Bx 4.3
and
.Nx 1.2 ,
respectively.
The
.Fn remquo
and
.Fn remquof
functions were added in
.Ox 4.4 .