/* Random walk test for random number generators */

#include	<stdlib.h>
#include	<stdio.h>
#include	<math.h>

#define	SKIPTIME	1000
#define	STEPS		500
#define IC	29573
#define IA	3877
#define IM	139968

double	myran(int *);
void Step(double *, double *, double);

int main(void)
{
	int i, j, seed1, seed2, seed3;
	double	x, y, x2, y2, x3, y3;

	seed1 = seed2 = seed3 = 145739853;   /* second seed: 358937541 */
	srand48(seed1);
	seed2 = seed2%IM;
	srand(seed3);

	x = y = x2 = y2 = x3 = y3 = 0.0;
	printf(" %d  %f  %f  %f  %f  %f  %f \n", 0, x, y, x2, y2, x3, y3);

	for(i=0;i<STEPS;i++)
	{
		for(j=0;j<SKIPTIME;j++)
		{
			Step(&x,&y,drand48());
			Step(&x2,&y2,myran(&seed2));
			Step(&x3,&y3,((double)rand()/(double)(RAND_MAX+1)));
		}
		printf(" %d  %f  %f  %f  %f  %f  %f\n",i+1, x, y, x2, y2, x3, y3);
	}
	return (0);
} /* end main */

void Step(double *xx, double *yy, double ran)
{
	double theta;
	theta = (2.0*M_PI)*ran;
	*xx += cos(theta);
	*yy += sin(theta);
}

double myran(int *seed)	/* random number generator from Numerical Recipes */

{
	*seed = ((*seed)*IA+IC) % IM;
	return((double)(*seed) / (double)IM);
}