Random Walk Simulation in 1D - Undesired output
Hello Guys, I am struggling with the code for simulation of Random Walk in 1D. It compiles, but the output to text file "Walk.txt" are all almost the same negative numbers. BTW I am a new to C programming, if you could look at the code and give your ideas about what is wrong with it. Here is the code itself:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#define N 10
double rndm(void)
{
return(double)rand()/RAND_MAX;
}
/*Function to simulate random walk in 1D*/
double walk(int start)
{
double a;
int i,x;
x=start;
for(i=0; i<N; i++)
{
a=rndm();
if(a<0.5) { /*Choses which direction to move in*/
(x=x+1);
}
if (a>0.5) {
(x=x-1);
}
}
return x;
}
/*Main Function*/
int main () {
FILE *fout;
int i,start,random[N],x;
srand(time(NULL));
fout=fopen("walk.txt", "w"); //Open The File
printf("What would you like the initial x position to be?\n:");
scanf("%d", &start); //Define Start position for x
for(i=0; i<N; i++) {
x=walk(start); // Generates Random Number
random[i]=x;
fprintf(fout, "%d\n", random[i]); // Writes Number To File
}
double p = 0;
for (i=0; i<N; i++){
p+=(random[i]-start)*(random[i]-start);}
p=p/N;
fprintf(fout, "%lf\n",p);
fclose(fout);
return 0;
}
In this part, i've tried to calculate the mean square displacement (position):
Code:
double p = 0;
for (i=0; i<N; i++){
p+=(random[i]-start)*(random[i]-start);}
p=p/N;
fprintf(fout, "%lf\n",p);
fclose(fout);
return 0;
}
And the output in "Walk.txt" is :
Code:
-1079135414
-1079135418
-1079135418
-1079135406
-1079135418
-1079135416
-1079135418
-1079135416
-1079135414
-1079135416
12.400000
