1.\" $NetBSD: copysign.3,v 1.4 2017/09/28 15:03:18 maya 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 September 28, 2017 28.Dt COPYSIGN 3 29.Os 30.Sh NAME 31.Nm copysign , 32.Nm copysignf , 33.Nm copysignl 34.Nd functions to manipulate signs 35.Sh LIBRARY 36.Lb libm 37.Sh SYNOPSIS 38.In math.h 39.Ft double 40.Fn copysign "double x" "double y" 41.Ft float 42.Fn copysignf "float x" "float y" 43.Ft long double 44.Fn copysignl "long double x" "long double y" 45.In tgmath.h 46.Ft real-floating 47.Fn copysign "real-floating x" "real-floating y" 48.Sh DESCRIPTION 49The 50.Fn copysign , 51.Fn copysignf , 52and 53.Fn copysignl 54functions return a value whose absolute value matches 55.Fa x , 56but whose sign bit is taken from 57.Fa y . 58.Sh RETURN VALUES 59Upon successful completion, 60all three functions return a value with the magnitude of 61.Fa x 62and the sign of 63.Fa y . 64If 65.Fa x 66is 67\*(Na , 68the functions return a 69\*(Na 70with the sign of 71.Fa y . 72.Sh SEE ALSO 73.Xr math 3 , 74.Xr signbit 3 75.Sh STANDARDS 76The described functions conform to 77.St -isoC-99 . 78.\" 79.\" XXX: Verify this. 80.\" 81.\" The functions are also recommended by 82.\" .St -ieee754 83.\" 84.\" .Sh HISTORY 85.\" 86.\" XXX: Fill this. 87.\" 88.\" These functions first appeared in ???. 89.\" 90.Sh CAVEATS 91Note that on implementations that represent a signed zero 92but do not treat negative zero consistently in arithmetic operations, 93these functions may regard the sign of zero as positive. 94