1.\" $NetBSD: isnan.3,v 1.3 2017/09/27 18:55:50 maya 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 September 27, 2017 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.Sh RETURN VALUES 56The 57.Fn isnan 58macro returns a non-zero value if the value of 59.Fa x 60is a NaN. 61Otherwise 0 is returned. 62.Sh SEE ALSO 63.Xr fpclassify 3 , 64.Xr isfinite 3 , 65.Xr isinf 3 , 66.Xr isinff 3 , 67.Xr isnanf 3 , 68.Xr isnormal 3 , 69.Xr math 3 , 70.Xr signbit 3 71.Rs 72.%T "IEEE Standard for Binary Floating-Point Arithmetic" 73.%Q ANSI 74.%R Std 754-1985 75.Re 76.Sh STANDARDS 77The 78.Fn isnan 79macro conforms to 80.St -isoC-99 . 81.Sh CAVEATS 82On VAX the 83.Fn isnan 84function always returns 0, 85as the architecture doesn't support NaN. 86