100 lines
3.1 KiB
Groff
100 lines
3.1 KiB
Groff
|
.\" Copyright (c) 2007 David Schultz <das@FreeBSD.org>
|
||
|
|
.\" All rights reserved.
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" $FreeBSD$
|
||
|
|
.\"
|
||
|
|
.Dd December 16, 2007
|
||
|
|
.Dt NAN 3
|
||
|
|
.Os
|
||
|
|
.Sh NAME
|
||
|
|
.Nm nan ,
|
||
|
|
.Nm nanf ,
|
||
|
|
.Nm nanl
|
||
|
|
.Nd quiet \*(Nas
|
||
|
|
.Sh LIBRARY
|
||
|
|
.Lb libm
|
||
|
|
.Sh SYNOPSIS
|
||
|
|
.In math.h
|
||
|
|
.Ft double
|
||
|
|
.Fn nan "const char *s"
|
||
|
|
.Ft float
|
||
|
|
.Fn nanf "const char *s"
|
||
|
|
.Ft long double
|
||
|
|
.Fn nanl "const char *s"
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
The
|
||
|
|
.Dv NAN
|
||
|
|
macro expands to a quiet \*(Na (Not A Number).
|
||
|
|
Similarly, each of the
|
||
|
|
.Fn nan ,
|
||
|
|
.Fn nanf ,
|
||
|
|
and
|
||
|
|
.Fn nanl
|
||
|
|
functions generate a quiet \*(Na value without raising an invalid exception.
|
||
|
|
The argument
|
||
|
|
.Fa s
|
||
|
|
should point to either an empty string or a hexadecimal representation
|
||
|
|
of a non-negative integer (e.g., "0x1234".)
|
||
|
|
In the latter case, the integer is encoded in some free bits in the
|
||
|
|
representation of the \*(Na, which sometimes store
|
||
|
|
machine-specific information about why a particular \*(Na was generated.
|
||
|
|
There are 22 such bits available for
|
||
|
|
.Vt float
|
||
|
|
variables, 51 bits for
|
||
|
|
.Vt double
|
||
|
|
variables, and at least 51 bits for a
|
||
|
|
.Vt long double .
|
||
|
|
If
|
||
|
|
.Fa s
|
||
|
|
is improperly formatted or represents an integer that is too large,
|
||
|
|
then the particular encoding of the quiet \*(Na that is returned
|
||
|
|
is indeterminate.
|
||
|
|
.Sh COMPATIBILITY
|
||
|
|
Calling these functions with a non-empty string isn't portable.
|
||
|
|
Another operating system may translate the string into a different
|
||
|
|
\*(Na encoding, and furthermore, the meaning of a given \*(Na encoding
|
||
|
|
varies across machine architectures.
|
||
|
|
If you understood the innards of a particular platform well enough to
|
||
|
|
know what string to use, then you would have no need for these functions
|
||
|
|
anyway, so don't use them.
|
||
|
|
Use the
|
||
|
|
.Dv NAN
|
||
|
|
macro instead.
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Xr fenv 3 ,
|
||
|
|
.Xr ieee 3 ,
|
||
|
|
.Xr isnan 3 ,
|
||
|
|
.Xr math 3 ,
|
||
|
|
.Xr strtod 3
|
||
|
|
.Sh STANDARDS
|
||
|
|
The
|
||
|
|
.Fn nan ,
|
||
|
|
.Fn nanf ,
|
||
|
|
and
|
||
|
|
.Fn nanl
|
||
|
|
functions and the
|
||
|
|
.Dv NAN
|
||
|
|
macro conform to
|
||
|
|
.St -isoC-99 .
|