June 2018 Update

Task/Mandelbrot-set/Metapost/mandelbrot-set-1.metapost

@@ -0,0 +1,44 @@
+prologues:=3;
+outputtemplate:="%j-%c.svg";
+outputformat:="svg";
+
+
+def mandelbrot(expr maxX, maxY) =
+  max_iteration := 500;
+
+  color col[];
+  for i := 0 upto max_iteration:
+    t := i / max_iteration;
+    col[i] = (t,t,t);
+  endfor;
+
+
+  for px := 0 upto maxX:
+    for py := 0 upto maxY:
+      xz := px * 3.5 / maxX - 2.5;  % (-2.5,1)
+      yz := py * 2 / maxY - 1;      % (-1,1)
+
+      x := 0;
+      y := 0;
+
+      iteration := 0;
+
+      forever: exitunless ((x*x + y*y < 4) and (iteration < max_iteration));
+        xtemp := x*x - y*y + xz;
+        y := 2*x*y + yz;
+        x := xtemp;
+        iteration := iteration + 1;
+      endfor;
+
+      draw (px,py) withpen pencircle withcolor col[iteration];
+
+    endfor;
+  endfor;
+enddef;
+
+
+beginfig(1);
+  mandelbrot(200, 150);
+endfig;
+
+end

Task/Mandelbrot-set/Metapost/mandelbrot-set-2.metapost

@@ -0,0 +1 @@
+mpost -numbersystem="double" mandelbrot.mp