use vastly more efficiant but less beautiful code for the real calc loop

diff --git a/xulapp/chrome/mandelbrot/content/mandelbrot.js b/xulapp/chrome/mandelbrot/content/mandelbrot.js
index 4dd2a4b248e03a05b212e030a04c4c37bd54857c..440911348f03d47ef5c8628c08776b28aeb5611e 100644 (file)
--- a/xulapp/chrome/mandelbrot/content/mandelbrot.js
+++ b/xulapp/chrome/mandelbrot/content/mandelbrot.js
@@ -48,11 +48,25 @@ function complex(aReal, aImag) {
 }
 
 function mandelbrotValue (aC, aIterMax) {
-  var Z = new complex(0.0, 0.0);
+  /* XXX: this would be nice code but it looks like JS objects are too heavy for this.
+  let Z = new complex(0.0, 0.0);
   for (var iter = 0; iter < aIterMax; iter++) {
     Z = Z.square().add(aC);
     if (Z.r * Z.r + Z.i * Z.i > 256) { break; }
   }
+  */
+
+  // highly optimized code for fast calculation
+  let Cr = aC.r, Ci = aC.i;
+  let Zr = 0.0, Zi = 0.0;
+  let Zr2 = Zr * Zr, Zi2 = Zi * Zi;
+  for (var iter = 0; iter < aIterMax; iter++) {
+    Zi = 2 * Zr * Zi + Ci;
+    Zr = Zr2 - Zi2 + Cr;
+
+    Zr2 = Zr * Zr; Zi2 = Zi * Zi;
+    if (Zr2 + Zi2 > 256) { break; }
+  }
   return iter;
 }