.\"	$NetBSD: nan.3,v 1.5 2016/08/27 02:56:26 dholland Exp $
.\"
.\" Copyright (c) 2006 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Klaus Klein.
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.Dd March 15, 2006
.Dt NAN 3
.Os
.Sh NAME
.Nm nan ,
.Nm nanf ,
.Nm nanl
.Nd return quiet NaN
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn nan "const char *tagp"
.Ft float
.Fn nanf "const char *tagp"
.Ft long double
.Fn nanl "const char *tagp"
.Sh DESCRIPTION
The call
.Fn nan "\*qn-char-sequence\*q"
is equivalent to the call
.Fn strtod "\*qNAN(n-char-sequence)\*q" "NULL" .
The call
.Fn nan "\*q\*q"
is equivalent to the call
.Fn strtod "\*qNAN()\*q" "NULL" .
.Pp
The
.Fn nanf
and
.Fn nanl
functions are equivalent to
.Fn nan
but substituting
.Fn strtof
and
.Fn strtold ,
respectively.
.Sh RETURN VALUES
.Ss IEEE 754
The
.Fn nan ,
.Fn nanf ,
and
.Fn nanl
functions return a quiet NaN as specified by
.Fa tagp .
.Ss VAX
The
.Fn nan ,
.Fn nanf ,
and
.Fn nanl
functions return zero.
.Sh SEE ALSO
.Xr math 3 ,
.Xr strtod 3
.Sh STANDARDS
The
.Fn nan ,
.Fn nanf ,
and
.Fn nanl
functions conform to
.St -isoC-99 .