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.\" $NetBSD: copysign.3,v 1.1 2011/04/13 04:57:10 jruoho Exp $
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.\"
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.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd April 13, 2011
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.Dt COPYSIGN 3
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.Os
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.Sh NAME
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.Nm copysign ,
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.Nm copysignf ,
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.Nm copysignl
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.Nd functions to manipulate signs
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.Sh LIBRARY
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.Lb libm
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.Sh SYNOPSIS
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.In math.h
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.Ft double
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.Fn copysign "double x" "double y"
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.Ft float
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.Fn copysignf "float x" "float y"
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.Ft long double
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.Fn copysignl "long double x" "long double y"
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.Sh DESCRIPTION
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The
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.Fn copysign ,
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.Fn copysignf ,
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and
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.Fn copysignl
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functions return a value whose absolute value matches
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.Fa x ,
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but whose sign bit is taken from
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.Fa y .
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.Sh RETURN VALUES
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Upon successful completion,
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all three functions return a value with the magnitude of
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.Fa x
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and the sign of
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.Fa y .
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If
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.Fa x
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is
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\*(Na ,
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the functions return a
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\*(Na
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with the sign of
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.Fa y .
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.Sh SEE ALSO
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.Xr math 3 ,
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.Xr signbit 3
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.Sh STANDARDS
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The described functions conform to
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.St -isoC-99 .
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.\"
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.\" XXX: Verify this.
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.\"
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.\" The functions are also recommended by
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.\" .St -ieee754
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.\"
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.\" .Sh HISTORY
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.\"
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.\" XXX: Fill this.
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.\"
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.\" These functions first appeared in ???.
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.\"
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.Sh CAVEATS
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Note that on implementations that represent a signed zero
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but do not treat negative zero consistently in arithmetic operations,
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these functions may regard the sign of zero as positive.
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