minix/lib/libc/gen/isnan.3

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.\" $NetBSD: isnan.3,v 1.2 2004/03/04 23:49:31 wiz Exp $
.\"
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.\" From: @(#)isinf.3 8.2 (Berkeley) 1/29/94
.\" from: NetBSD: isinf.3,v 1.10 2003/08/07 16:42:52 agc Exp
.\"
.Dd March 5, 2004
.Dt ISNAN 3
.Os
.Sh NAME
.Nm isnan
.Nd test for not-a-number
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In math.h
.Ft int
.Fn isnan "real-floating x"
.Sh DESCRIPTION
The
.Fn isnan
macro determines whether its argument
.Fa x
is not-a-number
.Pq Dq NaN .
An argument represented in a format wider than its semantic type is
converted to its semantic type first.
The determination is then based on the type of the argument.
.Ss IEEE 754
It is determined whether the value of
.Fa x
is a NaN.
.Ss VAX
NaNs are not supported.
.Sh RETURN VALUES
The
.Fn isnan
macro returns a non-zero value if the value of
.Fa x
is a NaN.
Otherwise 0 is returned.
.Sh SEE ALSO
.Xr fpclassify 3 ,
.Xr isfinite 3 ,
.Xr isinf 3 ,
.Xr isinff 3 ,
.Xr isnanf 3 ,
.Xr isnormal 3 ,
.Xr math 3 ,
.Xr signbit 3
.Rs
.%T "IEEE Standard for Binary Floating-Point Arithmetic"
.%Q ANSI
.%R Std 754-1985
.Re
.Sh STANDARDS
The
.Fn isnan
macro conforms to
.St -isoC-99 .