random_.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static char	*sccsid = " @(#)random_.c	4.1	(ULTRIX)	7/3/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1986 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/************************************************************************
*
*			Modification History
*
*	David Metsky		10-Jan-86
*
* 001	Added from BSD 4.3 version as part of upgrade.
*
*	Based on:	random_.c	5.2		6/7/85
*
*************************************************************************/
/*
 * Routines to return random values
 *
 * calling sequence:
 *	double precision d, drandm
 *	i = irandm(iflag)
 *	x = random(iflag)
 *	d = drandm(iflag)
 * where:
 *	If arg is nonzero, generator is restarted and value is returned.
 *	If arg is 0, next value is returned.
 *	Integer values will range from 0 thru 2147483647 (see random(3)).
 *	Real values will range from 0.0 thru 1.0 .
 */

#if	vax
#define	RANDMAX		2147483647
#else	vax
	UNKNOWN MACHINE!
#endif	vax

long irandm_(iarg)
long *iarg;
{
	if (*iarg) srandom((int)*iarg);
	return( random() );
}

float random_(iarg)
long *iarg;
{
	if (*iarg) srandom((int)*iarg);
	return( (float)(random())/(float)RANDMAX );
}

double drandm_(iarg)
long *iarg;
{
	if (*iarg) srandom((int)*iarg);
	return( (double)(random())/(double)RANDMAX );
}