Random Walk

/* simple random walk simulation */


#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>

FILE *output;
time_t t;

main()
{
int i;
double xrand,yrand;
double x, y, randwalkarr[10001];
output= fopen ("randwalk4.dat", "w"); /* external file name */

for (i=0; i<=10000; i++)
    randwalkarr [i]=0.0; /* clear array */
       srand((unsigned) time(&t)); /* set the number generator */
    x=0.0; y=0.0;

for (i=1;i<=10000; i++)
{

/* generate x random number */

   xrand=rand()%1000;
   xrand=xrand/1000;
if(xrand<0.5)

x=x+1.0;

else

x=x-1.0;

/* generate y random number */

yrand=rand()%1000;
yrand=yrand/1000;

if(yrand<0.5)
y=y+1.0;

else

y=y-1.0;

randwalkarr[i] = sqrt(x*x+y*y);/* store randwalkarr to total */

}
/* Write values to file */
for (i=0; i<=100; i++)
{
fprintf(output,"%d %lf\n", i, randwalkarr[i*100]);
}
fclose (output);
}