Question

I have been running this random walk simulation for a while now and I keep getting an error EXC_BAD_ACCESS from Xcode. Its printing out a large part of the simulation though.

I think its running out of memory for some reason but I am not sure why.

If I go towards the end of the array I edited it so I don’t get within 100 spaces of the edge (by editing the variable steps to steps -100). This works but I would like to know whats going on.

Any help would be appreciated.

double** places;  
places = (double**) malloc(steps*sizeof(double*));  
for (int i = 0; i < steps; i++)places[i] = (double*) malloc(2*sizeof(double));  

for (i = 0; i< steps/*, exit*/; i++) {
    // Find the angle of movement 
    angle = getRand()*360; 
    // Take a step
    xPos+= STEP*cos(angle);
    yPos+= STEP*sin(angle);
    //Write Step to array
    places[i][1] = xPos;
    places[i][2] = yPos;
    //Write Step to File
    fprintf(ff, "%d %lf %lf\n",i,xPos,yPos);
}

Answer 1

Array indexes start at zero.

Did you mean to write this?

    places[i][0] = xPos; //Zeroth element is considered the first element
    places[i][1] = yPos; //Second element