xref: /minix3/lib/libc/gen/isnan.3 (revision 2fe8fb192fe7e8720e3e7a77f928da545e872a6a)
1.\"	$NetBSD: isnan.3,v 1.2 2004/03/04 23:49:31 wiz Exp $
2.\"
3.\" Copyright (c) 1991, 1993
4.\"	The Regents of the University of California.  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.\" 3. Neither the name of the University nor the names of its contributors
15.\"    may be used to endorse or promote products derived from this software
16.\"    without specific prior written permission.
17.\"
18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28.\" SUCH DAMAGE.
29.\"
30.\"     From: @(#)isinf.3	8.2 (Berkeley) 1/29/94
31.\"	from: NetBSD: isinf.3,v 1.10 2003/08/07 16:42:52 agc Exp
32.\"
33.Dd March 5, 2004
34.Dt ISNAN 3
35.Os
36.Sh NAME
37.Nm isnan
38.Nd test for not-a-number
39.Sh LIBRARY
40.Lb libc
41.Sh SYNOPSIS
42.In math.h
43.Ft int
44.Fn isnan "real-floating x"
45.Sh DESCRIPTION
46The
47.Fn isnan
48macro determines whether its argument
49.Fa x
50is not-a-number
51.Pq Dq NaN .
52An argument represented in a format wider than its semantic type is
53converted to its semantic type first.
54The determination is then based on the type of the argument.
55.Ss IEEE 754
56It is determined whether the value of
57.Fa x
58is a NaN.
59.Ss VAX
60NaNs are not supported.
61.Sh RETURN VALUES
62The
63.Fn isnan
64macro returns a non-zero value if the value of
65.Fa x
66is a NaN.
67Otherwise 0 is returned.
68.Sh SEE ALSO
69.Xr fpclassify 3 ,
70.Xr isfinite 3 ,
71.Xr isinf 3 ,
72.Xr isinff 3 ,
73.Xr isnanf 3 ,
74.Xr isnormal 3 ,
75.Xr math 3 ,
76.Xr signbit 3
77.Rs
78.%T "IEEE Standard for Binary Floating-Point Arithmetic"
79.%Q ANSI
80.%R Std 754-1985
81.Re
82.Sh STANDARDS
83The
84.Fn isnan
85macro conforms to
86.St -isoC-99 .
87