1.\"	$NetBSD: signbit.3,v 1.3 2008/04/30 13:10:50 martin Exp $
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3.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
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6.\" This code is derived from software contributed to The NetBSD Foundation
7.\" by Klaus Klein.
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30.Dd October 29, 2003
31.Dt SIGNBIT 3
32.Os
33.Sh NAME
34.Nm signbit
35.Nd test sign
36.Sh LIBRARY
37.Lb libc
38.Sh SYNOPSIS
39.In math.h
40.Ft int
41.Fn signbit "real-floating x"
42.Sh DESCRIPTION
43The
44.Fn signbit
45macro determines whether the sign of its argument value
46.Fa x
47is negative.
48An argument represented in a format wider than its semantic type is
49converted to its semantic type first.
50The determination is then based on the type of the argument.
51.Ss IEEE754
52The sign is determined for all values, including infinities, zeroes,
53and NaNs
54.Ss VAX
55The sign is determined for finites, true zeros, and dirty zeroes;
56for ROPs the sign is reported negative.
57.Sh RETURN VALUES
58The
59.Fn signbit
60macro returns a non-zero value if the sign of its value
61.Fa x
62is negative.
63Otherwise 0 is returned.
64.Sh ERRORS
65No errors are defined.
66.Sh SEE ALSO
67.Xr fpclassify 3 ,
68.Xr isfinite 3 ,
69.Xr isnormal 3 ,
70.Xr math 3
71.Sh STANDARDS
72The
73.Fn signbit
74macro conforms to
75.St -isoC-99 .
76