int centre = buffer_size / 2;
double pi2 = 2.0 * Math.PI;
int size2 = buffer_size - 2;
short q[][] = new short[buffer_size][buffer_size];
randGen.randomize(seed);
q[centre][centre] = 1;
double r1 = 3.0;
double r2 = 3.0 * r1;
for (int i = 0; i < _max_iter; i++) {
double phi = pi2 * randGen.random();