.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
.\" Modified 2002-07-27 by Walter Harms
.\" 	(walter.harms@informatik.uni-oldenburg.de)
.\"
.\" Japanese Version Copyright (c) 1997 YOSHINO Takashi
.\"       all rights reserved.
.\" Translated 1997-01-21, YOSHINO Takashi <yoshino@civil.jcn.nihon-u.ac.jp>
.\" Updated 2003-10-15, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-11-19, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\"
.TH FREXP 3 2010-09-20 "" "Linux Programmer's Manual"
.\"O .SH NAME
.SH 名前
.\"O frexp, frexpf, frexpl \- convert floating-point number to fractional
.\"O and integral components
frexp, frexpf, frexpl \- 浮動小数点実数を小数成分と整数成分に変換する
.\"O .SH SYNOPSIS
.SH 書式
.nf
.B #include <math.h>
.sp
.BI "double frexp(double " x ", int *" exp );
.br
.BI "float frexpf(float " x ", int *" exp );
.br
.BI "long double frexpl(long double " x ", int *" exp );
.fi
.sp
.\"O Link with \fI\-lm\fP.
\fI\-lm\fP でリンクする。
.sp
.in -4n
.\"O Feature Test Macro Requirements for glibc (see
.\"O .BR feature_test_macros (7)):
glibc 向けの機能検査マクロの要件
.RB ( feature_test_macros (7)
参照):
.in
.sp
.ad l
.BR frexpf (),
.BR frexpl ():
.RS 4
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad
.\"O .SH DESCRIPTION
.SH 説明
.\"O The
.\"O .BR frexp ()
.\"O function is used to split the number \fIx\fP into a
.\"O normalized fraction and an exponent which is stored in \fIexp\fP.
.BR frexp ()
関数は浮動小数点実数 \fIx\fP を正規化小数と指数に分解し、
指数を *\fIexp\fP に格納する。
.\"O .SH "RETURN VALUE"
.SH 返り値
.\"O The
.\"O .BR frexp ()
.\"O function returns the normalized fraction.
.\"O If the argument \fIx\fP is not zero,
.\"O the normalized fraction is \fIx\fP times a power of two,
.\"O and its absolute value is always in the range 1/2 (inclusive) to
.\"O 1 (exclusive), that is, [0.5,1).
.BR frexp ()
関数は正規化小数を返す。
引数 \fIx\fP がゼロでない場合、この正規化小数は
\fIx\fP に 2 の累乗を乗じたものであり、その絶対値は
常に 1/2 以上 1 未満、つまり [0.5,1) となる。

.\"O If \fIx\fP is zero, then the normalized fraction is
.\"O zero and zero is stored in \fIexp\fP.
\fIx\fP がゼロの場合、正規化小数はゼロになり
*\fIexp\fP にはゼロが格納される。

.\"O If
.\"O .I x
.\"O is a NaN,
.\"O a NaN is returned, and the value of
.\"O .I *exp
.\"O is unspecified.
.I x
が NaN の場合、NaN が返される。
.I *exp
の値は不定である。

.\"O If
.\"O .I x
.\"O is positive infinity (negative infinity),
.\"O positive infinity (negative infinity) is returned, and the value of
.\"O .I *exp
.\"O is unspecified.
.I x
が正の無限大 (負の無限大) の場合、
正の無限大 (負の無限大) が返される。
.I *exp
の値は不定である。
.\"O .SH ERRORS
.SH エラー
.\"O No errors occur.
エラーは発生しない。
.\"O .SH "CONFORMING TO"
.SH 準拠
C99, POSIX.1-2001.
.\"O The variant returning
.\"O .I double
.\"O also conforms to
.\"O SVr4, 4.3BSD, C89.
.I double
版の関数は SVr4, 4.3BSD, C89 にも準拠している。
.\"O .SH EXAMPLE
.SH 例
.\"O The program below produces results such as the following:
このプログラムを実行すると以下のような結果となる:
.sp
.nf
.in +4n
.RB "$" " ./a.out 2560"
frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
.RB "$" " ./a.out \-4"
frexp(\-4, &e) = \-0.5: \-0.5 * 2^3 = -4
.in
.fi
.\"O .SS Program source
.SS プログラムのソース
\&
.nf
#include <math.h>
#include <float.h>
#include <stdio.h>
#include <stdlib.h>

int
main(int argc, char *argv[])
{
    double x, r;
    int exp;

    x = strtod(argv[1], NULL);
    r = frexp(x, &exp);

    printf("frexp(%g, &e) = %g: %g * %d^%d = %g\\n",
           x, r, r, FLT_RADIX, exp, x);
    exit(EXIT_SUCCESS);
}
.fi
.\"O .SH "SEE ALSO"
.SH 関連項目
.BR ldexp (3),
.BR modf (3)