/*******************************************************************

cell.c - started 6/18/95 - Eric Weeks
just a quick program to make sure my a2ps program is working
also I'm killing time

v02:  6-19-95	taken from "cell1bak.c"; changed to do real numbers
v03:  8-30-96: cleaned up a little bit.

email: weeks@physics.emory.edu
web: http://www.physics.emory.edu/~weeks/

to compile: cc -o cell cell3.c -lm

 *******************************************************************/
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include <stdio.h>
#define PI 3.14159265358979323846264338328
#define EE 2.71828182845904523536
#define SIZE 1000



void rand_init();
double drnd();
char *prgname;

main(argc,argv)
int argc;
char **argv;
{
	int t,r,bit;
	double array[SIZE][2],newcell;
	int a,b,c,num;
	extern int optind;
	extern char *optarg;
	double gamma,alpha[3];

	num = 500;
	rand_init();
	alpha[0] = 2.0*drnd()-1.0;
	alpha[1] = 2.0*drnd()-1.0;
	alpha[2] = 2.0*drnd()-1.0;
	gamma = drnd()*1.0-0.5;
	while ((c = getopt(argc, argv, "hn:u:a:b:c:d:")) != EOF)
	switch (c)  {
	case 'h':  fprintf(stderr,"Usage: %s [options]\n",argv[0]);
fprintf(stderr,"Options:\n");
fprintf(stderr,"x_n new = A x_{n-1} + B x_n + C x_{n+1} + D\n\n");
fprintf(stderr," -n # : number of cells [%d]\n",num);
fprintf(stderr," -a # : change A, coefficient of a_{n-1}\n");
fprintf(stderr," -b # : change B, coefficient of a_n\n");
fprintf(stderr," -c # : change C, coefficient of a_{n+1}\n");
fprintf(stderr," -d # : change D, the constant\n");
fprintf(stderr,"\nOutput suitable for programs a2ps or a2ppm\n");
			exit(1);
			break;
	case 'n': num = atoi(optarg);
			if (num>SIZE)  {
				fprintf(stderr,"ERROR: -n is too large\n");
				fprintf(stderr,"       change value of SIZE in program\n");
				fprintf(stderr,"       currently SIZE = %d\n",SIZE);
				exit(1);
			}
			break;
	case 'a': alpha[0] = atof(optarg);
			break;
	case 'b': alpha[1] = atof(optarg);
			break;
	case 'c': alpha[2] = atof(optarg);
			break;
	case 'd': gamma = atof(optarg);
			break;
        }

	fprintf(stderr,"%f %f %f %f\n",gamma,alpha[0],alpha[1],alpha[2]);

	/* random initial conditions */
	for (t=0;t<num;t++)
		array[t][0] = drnd();

	bit = 1;
	printf("%d %d\n",num,num);	/* size of picture for a2ps,a2ppm */
	for (t=0;t<num;t++)  {
		bit = 1 - bit;
		for (r=0;r<num;r++)  {
			/* a = left neighbor, b = right neighbor */
			a = ((r==0) ? (num-1) : (r-1));
			b = ((r==(num-1)) ? (0) : (r+1));
			newcell = gamma + alpha[0]*array[a][bit];
			newcell += alpha[1]*array[r][bit] +alpha[2]*array[b][bit];
			newcell = fmod(newcell,1.0);
			if (newcell<0.0)  newcell++;
			array[r][1-bit] = newcell;
			printf("%.0f ",newcell*256);
		}
		printf("\n");
	}
} 






/* This produces a random number between 0 and 1 */
double drnd()
{
	double value;
	long n,x;

	x = lrand48();
	n = (1024*1024*1024 - 1) + 1024*1024*1024;
	value = (1.0*x)/(1.0*n);
	return value;
}



/* initialize random number generator */
void rand_init()  {
	int seed;
	time_t timenow;
	time(&timenow);
	seed=timenow % 100000;
	srand48(seed);
}