76 lines
2.5 KiB
Groff
76 lines
2.5 KiB
Groff
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.\" $NetBSD: signbit.3,v 1.3 2008/04/30 13:10:50 martin Exp $
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.\"
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.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Klaus Klein.
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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 October 29, 2003
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.Dt SIGNBIT 3
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.Os
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.Sh NAME
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.Nm signbit
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.Nd test sign
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In math.h
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.Ft int
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.Fn signbit "real-floating x"
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.Sh DESCRIPTION
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The
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.Fn signbit
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macro determines whether the sign of its argument value
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.Fa x
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is negative.
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An argument represented in a format wider than its semantic type is
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converted to its semantic type first.
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The determination is then based on the type of the argument.
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.Ss IEEE754
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The sign is determined for all values, including infinities, zeroes,
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and NaNs
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.Ss VAX
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The sign is determined for finites, true zeros, and dirty zeroes;
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for ROPs the sign is reported negative.
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.Sh RETURN VALUES
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The
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.Fn signbit
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macro returns a non-zero value if the sign of its value
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.Fa x
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is negative.
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Otherwise 0 is returned.
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.Sh ERRORS
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No errors are defined.
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.Sh SEE ALSO
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.Xr fpclassify 3 ,
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.Xr isfinite 3 ,
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.Xr isnormal 3 ,
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.Xr math 3
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.Sh STANDARDS
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The
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.Fn signbit
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macro conforms to
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.St -isoC-99 .
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