1.\" $NetBSD: copysign.3,v 1.1 2011/04/13 04:57:10 jruoho Exp $
2.\"
3.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
4.\" All rights reserved.
5.\"
6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions
8.\" are met:
9.\" 1. Redistributions of source code must retain the above copyright
10.\"    notice, this list of conditions and the following disclaimer.
11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\"    notice, this list of conditions and the following disclaimer in the
13.\"    documentation and/or other materials provided with the distribution.
14.\"
15.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
16.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
17.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
18.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
19.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
21.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25.\" POSSIBILITY OF SUCH DAMAGE.
26.\"
27.Dd $Mdocdate: February 9 2014 $
28.Dt COPYSIGN 3
29.Os
30.Sh NAME
31.Nm copysign ,
32.Nm copysignf
33.Nd functions to manipulate signs
34.Sh LIBRARY
35.Lb libm
36.Sh SYNOPSIS
37.In math.h
38.Ft double
39.Fn copysign "double x" "double y"
40.Ft float
41.Fn copysignf "float x" "float y"
42.Sh DESCRIPTION
43The
44.Fn copysign
45and
46.Fn copysignf
47functions return a value whose absolute value matches
48.Fa x ,
49but whose sign bit is taken from
50.Fa y .
51.Sh RETURN VALUES
52Upon successful completion,
53all three functions return a value with the magnitude of
54.Fa x
55and the sign of
56.Fa y .
57If
58.Fa x
59is
60\*(Na ,
61the functions return a
62\*(Na
63with the sign of
64.Fa y .
65.Sh SEE ALSO
66.Xr math 3 ,
67.Xr signbit 3
68.Sh STANDARDS
69The described functions conform to
70.St -isoC-99 .
71.\"
72.\" XXX: Verify this.
73.\"
74.\" The functions are also recommended by
75.\" .St -ieee754
76.\"
77.\" .Sh HISTORY
78.\"
79.\" XXX: Fill this.
80.\"
81.\" These functions first appeared in ???.
82.\"
83.Sh CAVEATS
84Note that on implementations that represent a signed zero
85but do not treat negative zero consistently in arithmetic operations,
86these functions may regard the sign of zero as positive.
87