.\" 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.\" manual page may be incorrect or out-of-date.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 Sat Jul 24 19:46:03 1993 by Rik Faith (faith@cs.unc.edu)
.\"
.\" Japanese Version Copyright (c) 1997 YOSHINO Takashi
.\"       all rights reserved.
.\" Translated Mon Jan 20 20:04:05 JST 1997
.\"       by YOSHINO Takashi <yoshino@civil.jcn.nihon-u.ac.jp>
.\"
.\" WORD: internal buffer  Хåե
.\"
.TH DRAND48 3  2007-07-26 "" "Linux Programmer's Manual"
.SH ̾
drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48,
lcong48 \- ʬۤ뵿ؿ
.SH 
.nf
.B #include <stdlib.h>
.sp
.B double drand48(void);
.sp
.BI "double erand48(unsigned short " xsubi [3]);
.sp
.B long int lrand48(void);
.sp
.BI "long int nrand48(unsigned short " xsubi [3]);
.sp
.B long int mrand48(void);
.sp
.BI "long int jrand48(unsigned short " xsubi [3]);
.sp
.BI "void srand48(long int " seedval );
.sp
.BI "unsigned short *seed48(unsigned short " seed16v [3]);
.sp
.BI "void lcong48(unsigned short " param [7]);
.fi
.sp
.in -4n
glibc εǽޥ׷
.RB ( feature_test_macros (7)
):
.in
.sp
.ad l
嵭Ƥδؿ:
.\" .BR drand48 (),
.\" .BR erand48 (),
.\" .BR lrand48 (),
.\" .BR nrand48 (),
.\" .BR mrand48 (),
.\" .BR jrand48 (),
.\" .BR srand48 (),
.\" .BR seed48 (),
.\" .BR lcong48 ():
_SVID_SOURCE || _XOPEN_SOURCE
.ad b
.SH 
δؿƱ르ꥺ 48ӥå黻Ѥ
롣
.PP
ؿ
.BR drand48 ()

.BR erand48 ()
ϡ [0.0, 1.0) 
ʬۤư¿֤ͤ
.PP
ؿ
.BR lrand48 ()

.BR nrand48 ()
 0  2^31 δ֤ǰʬۤ
Υ֤
.PP
ؿ
.BR mrand48 ()

.BR jrand48 ()

\-2^31  2^31 δ֤ǰʬۤդ֤
.PP
ؿ
.BR srand48 (),
.BR seed48 (),
.BR lcong48 ()
Ͻؿ
Ǥ롣
ؿ
.BR drand48 (),
.BR lrand48 (),
.BR mrand48 ()

ѤˡνؿΤ줫Ƥ֤٤Ǥ롣
ؿ
.BR erand48 (),
.BR nrand48 (),
.BR jrand48 ()
Ͻ
ؿƤ֤ȤɬפȤʤ
.PP
Ƥ뤹٤Ƥδؿ 48ӥåȤ
 (\fIXi\fP) 뤳Ȥ
ǽƤ롣ˡϰʲƱμˤ롣
.sp
.nf
.RS
.B Xn+1 = (aXn + c) mod m,
.RE
.fi
.sp
 n >= 0 Ǥ롣
ѥ᡼ \fIm\fP = 2^48 Ǥ뤿ᡢ48ӥå黻ԤƤ롣
.BR lcong48 ()
ƤФƤʤ硢\fIa\fP  \fIc\fP ϰʲμͿ롣
.sp
.nf
.RS
.B a = 0x5DEECE66D
.B c = 0xB
.RE
.fi
.sp
ؿ
.BR drand48 (),
.BR erand48 (),
.BR lrand48 (),
.BR nrand48 (),
.BR mrand48 (),
.BR jrand48 ()
֤ͤϼΤ褦ˤƷ׻롣
Ϥˡ48ӥåȤ \fIXi\fP ׻롣
ơ֤٤ǡη˰¸Ŭڤ
ӥåȿ \fIXi\fP ξ̥ӥåȤ饳ԡ롣
Ǹˡ֤ͤͤѴ롣
.PP
ؿ
.BR drand48 (),
.BR lrand48 (),
.BR mrand48 ()

Ǹ줿48ӥåȤ \fIXi\fP Хåե˳Ǽ롣
ηΰ \fIxsubi\fP ˸ġ \fIXi\fP ͤ
ǼǤ褦ΰݤ뤳Ȥ
ؿ
.BR erand48 (),
.BR nrand48 (),
.BR jrand48 ()
ϡ
ƤӽФ¦Υץ׵᤹롣
δؿϡϤƤδؿƤ \fIXi\fP νͤ
뤳Ȥǽ롣
.PP
ؿ
.BR srand48 ()
ϡ\fIXi\fP 
32ӥåȤ \fIseedval\fP ꤹ롣
̤16ӥåȤϡŬ˷줿ͤǤ0x330Eꤵ롣
.PP
ؿ
.BR seed48 ()
ϡ\fIXi\fP ͤ
η򤷤Ǥ \fIseed16v\fP ǻꤵ줿 48ӥåȤͤꤹ롣
\fIXi\fP ͤХåե˥ԡ졢ΥХåեؤΥݥ󥿤
.BR seed48 ()
ˤä֤롣
.PP
ؿ
.BR lcong48 ()
ϻѼԤ \fIXi\fP, \fIa\fP, \fIc\fP 
ͤꤹ뤿δؿǤ롣
η򤷤ǤϤ줾졢\fIparam[0-2]\fP  \fIXi\fP 
\fIparam[3-5]\fP  \fIa\fP \fIparam[6]\fP  \fIc\fP ꤹ
Ǥ롣
.BR lcong48 ()
ƤФ줿ǡ
.BR srand48 ()

.BR seed48 ()
Ƥ֤ȡҤ \fIa\fP  \fIc\fP 
ɸͤƤꤵ롣
.SH 
SVr4, POSIX.1-2001.
.SH 
SVID 3 ǤϤδؿϻ٤Ƥ롣
SVID 3 Ǥ
.BR rand (3)
˻Ѥ٤ȵҤƤ롣
.SH Ϣ
.BR rand (3),
.BR random (3)