gauss.c

来自「speech signal process tools」· C语言 代码 · 共 41 行

/*
| This material contains proprietary software of Entropic Processing, Inc.
| Any reproduction, distribution, or publication without the the prior
| written permission of Entropic Processing, Inc. is strictly prohibited.
| Any public distribution of copies of this work authorized in writing by
| Entropic Processing, Inc. must bear the notice
|
|              "Copyright 1986 Entropic Processing, Inc."
|
| Written by:  S. Shankar Narayan
|
| Module:	gauss.c
| 
*/

#ifdef SCCS
static char *sccs_id = "@(#)gauss.c	1.2 4/21/86 (gauss.c)";
#endif
float gauss(dummy) /* gaussian random number generation */
float dummy;
{
	extern float rand();
	double sqrt(),log();
	static int flag = 1;
	double s,v1,v2;
	static double x1,x2;
	if (flag == 2) { flag = 1; return(x1);}
	do 
	    {
	     v1 = 2.0*rand(dummy);
	     v2 = 2.0*rand(dummy);
	     s = v1*v1+v2*v2;
	    }
	while (s > 1.0);
	x1 = sqrt(-2.0*log(s)/s);
	x2 = v2*x1;
	x1 = v1*x1;
	flag = 2;
	return (x2);
}