void genRandom() {
  for (int i=0; i<50; i++) {
    float u, v, s;
    do {
      u = random(-1, 1);
      v = random(-1, 1);
      s = u*u + v*v;
    }   
    while ( (s==0)||(s>=1) );

    data[i*2] = u * sqrt(-2*log(s)/s) + 79;
    data[i*2+1] = v * sqrt(-2*log(s)/s) + 79;
  }

  for (int i=0; i<50; i++) {
    float u, v, s;
    do {
      u = random(-1, 1);
      v = random(-1, 1);
      s = u*u + v*v;
    }   
    while ( (s==0)||(s>=1) );

    data[i*2+100] = u * sqrt(-2*log(s)/s) + 89;
    data[i*2+101] = v * sqrt(-2*log(s)/s) + 89;
  }

  for (int i=0; i<50; i++) {
    float u, v, s;
    do {
      u = random(-1, 1);
      v = random(-1, 1);
      s = u*u + v*v;
    }   
    while ( (s==0)||(s>=1) );

    data[i*2+200] = u * sqrt(-2*log(s)/s) + 81;
    data[i*2+201] = v * sqrt(-2*log(s)/s) + 81;
  }

  for (int i=0; i<50; i++) {
    float u, v, s;
    do {
      u = random(-1, 1);
      v = random(-1, 1);
      s = u*u + v*v;
    }   
    while ( (s==0)||(s>=1) );

    data[i*2+300] = u * sqrt(-2*log(s)/s) + 91;
    data[i*2+301] = v * sqrt(-2*log(s)/s) + 91;
  }
}