-- Fractal-Funktion
--   by Norbert Schuler  Norbert_Schuler@public.uni-hamburg.de
--   08.05.1995

-- Array Resolution
array_size = 200;

xm = array_size;
ym = array_size;

-- Default values for square fractal
x1 = -2;
x2 = 2;
y1 = -2;
y2 = 2;
xkkk = x1;
ykkk = y1;
stei_r := ((x2-x1) / xm):;
stei_i := ((y2-y1) / ym):;

max = 50;     -- max interation of loop

vr_back = 0;  -- changes may have funny effects
vi_back = 0;

color(x,y) = vr:=xkkk+(stei_r*x),
             vi:=ykkk+(stei_i*y),
             zrm:=vr_back,
             zim:=vi_back,
             z:=0,
             (zrh:=zrm,
              zrm:=zrm*zrm-zim*zim+vr,
              zim:=2*zrh*zim+vi,
              z:=z+1) while zrm*zrm+zim*zim<4 and z < max,
             z

arr[i,j] = color(i,j) dim [xm,ym];

Xmin=0; Xmax=xm; Ymin=0; Ymax=ym;
Zmin=0; Zmax =max;
image arr