void doApfelmannFloat() {

  const int radius = 16 * 1000 * 10;
  const float pmin = -2.25;
  const float pmax = 0.75;
  const float qmin = -1.5;
  const float qmax = 1.5;
  const int anzahl = 100;

  const float pdiff = pmax-pmin;
  const float qdiff = qmax-qmin;

  float xneu, yneu;
  float p, q, x, y;
  float xsq, ysq;
  volatile int   k;

  GDP_CLS();
  for (int xkoor=0; xkoor < 511; xkoor++  ) {
    for (int ykoor=0; ykoor < 255; ykoor++) {
            
      p = pdiff*xkoor/511+pmin;
      q = qdiff*ykoor/255+qmin;
     
      x = 0;
      y = 0;
      k = 0;
      
      do {
        xneu = x*x-y*y + p;
        yneu = 2*x*y + q;
        k++;
        x = xneu;
        y = yneu;
      } while (((x*x+y*y) < radius) && (k < anzahl));
     
      if ((k % 2) == 1) {
        GDP_MOVETO(xkoor, ykoor);
        GDP_CMD(0xFFFFFF70, 0b10100000);
      }
    }
  }
}