mirror of
https://gitlab.com/sortix/sortix.git
synced 2023-02-13 20:55:38 -05:00
5980be9b3c
This work is based in part on code from NetBSD libm, libc and kernel. The library is partly public domain and partly BSD-style licensed.
144 lines
3.3 KiB
Groff
144 lines
3.3 KiB
Groff
.\" $NetBSD: remainder.3,v 1.2 2011/09/18 05:33:14 jruoho Exp $
|
|
.\"
|
|
.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
|
|
.\"
|
|
.Dd September 18, 2011
|
|
.Dt REMAINDER 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm remainder ,
|
|
.Nm remainderf ,
|
|
.Nm remquo ,
|
|
.Nm remquof
|
|
.Nd remainder functions
|
|
.Sh LIBRARY
|
|
.Lb libm
|
|
.Sh SYNOPSIS
|
|
.In math.h
|
|
.Ft double
|
|
.Fn remainder "double x" "double y"
|
|
.Ft float
|
|
.Fn remainderf "float x" "float y"
|
|
.Ft double
|
|
.Fn remquo "double x" "double y" "int *quo"
|
|
.Ft float
|
|
.Fn remquof "float x" "float y" "int *quo"
|
|
.Sh DESCRIPTION
|
|
Provided that
|
|
.Fa y
|
|
\*(Ne 0 ,
|
|
the
|
|
.Fn remainder
|
|
and
|
|
.Fn remainderf
|
|
functions calculate the floating-point remainder
|
|
.Fa r
|
|
of
|
|
.Bd -ragged -offset indent
|
|
.Va r
|
|
=
|
|
.Va x - ny ,
|
|
.Ed
|
|
.Pp
|
|
where
|
|
.Fa n
|
|
is the integral value nearest to the exact value of
|
|
.Fa x
|
|
/
|
|
.Fa y .
|
|
If
|
|
.Bd -ragged -offset indent
|
|
.Va | n
|
|
-
|
|
.Va x / y |
|
|
= 1/2 ,
|
|
.Ed
|
|
.Pp
|
|
the value
|
|
.Fa n
|
|
is chosen to be even.
|
|
Consequently, the remainder is computed exactly and
|
|
.Va | r |
|
|
\*(Le
|
|
.Fa | y |
|
|
/ 2 .
|
|
.Pp
|
|
Also the
|
|
.Fn remquo
|
|
and
|
|
.Fn remquof
|
|
functions calculate the remainder as described above.
|
|
But these additionally use
|
|
.Fa quo
|
|
to store a value whose sign is the sign of
|
|
.Va x / y
|
|
and whose magnitude is congruent modulo
|
|
.Va 2^k
|
|
to the magnitude of the integral quotient of
|
|
.Va x / y ,
|
|
where
|
|
.Fa k
|
|
is an implementation-defined integer greater than or equal to 3.
|
|
.Pp
|
|
The rationale of the
|
|
.Fn remquo
|
|
family of functions relates to situations where
|
|
only few bits of the quotient are required.
|
|
The exact representation of the quotient may not be meaningful when
|
|
.Fa x
|
|
is large in magnitude compared to
|
|
.Fa y .
|
|
.Sh RETURN VALUES
|
|
The functions return the remainder independent of the rounding mode.
|
|
If
|
|
.Fa y
|
|
is zero ,
|
|
\*(Na
|
|
is returned and a domain error occurs.
|
|
A domain error occurs and a
|
|
\*(Na
|
|
is returned also when
|
|
.Fa x
|
|
is infinite but
|
|
.Fa y
|
|
is not a
|
|
\*(Na.
|
|
If either
|
|
.Fa x
|
|
or
|
|
.Fa y
|
|
is
|
|
\*(Na,
|
|
a
|
|
\*(Na
|
|
is always returned.
|
|
.Sh SEE ALSO
|
|
.Xr div 3 ,
|
|
.Xr fast_remainder32 3 ,
|
|
.Xr fmod 3 ,
|
|
.Xr math 3
|
|
.Sh STANDARDS
|
|
The described functions conform to
|
|
.St -isoC-99 .
|