1 files changed, 121 insertions, 0 deletions
diff --git a/Week15 Mandelbrot/src/com/camilstaps/mandelbrot/MandelbrotFractal.java b/Week15 Mandelbrot/src/com/camilstaps/mandelbrot/MandelbrotFractal.java
new file mode 100644
index 0000000..e0c0520
--- /dev/null
+++ b/Week15 Mandelbrot/src/com/camilstaps/mandelbrot/MandelbrotFractal.java
@@ -0,0 +1,121 @@
+/*
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Camil Staps <info@camilstaps.nl>
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.camilstaps.mandelbrot;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Class for calculating Mandelbrot numbers
+ * By remembering seen numbers, we can significantly decrease calculation time
+ * 
+ * @author Camil Staps
+ */
+public class MandelbrotFractal {
+    
+    /**
+     * Storage for previously calculated numbers
+     */
+    private static final Map<Point,Result> mandelNumbers = new HashMap<>();
+    
+    public static int mandelNumber(double x, double y, int repetitions) {
+        Point p = new Point(x, y);
+        return mandelNumber(p, repetitions);
+    }
+    
+    public static int mandelNumber(Point p, int repetitions) {
+        if (mandelNumbers.containsKey(p)) {
+            Result result = mandelNumbers.get(p);
+            if (repetitions < result.repetitions ||
+                    result.mandelNumber < result.repetitions) {
+                return result.mandelNumber;
+            } else {
+                calculateMandelNumber(p, repetitions, result);
+                return result.mandelNumber;
+            }
+        } else {
+            Result result = calculateMandelNumber(p, repetitions);
+            mandelNumbers.put(p, result);
+            return result.mandelNumber;
+        }
+    }
+    
+    protected static Result calculateMandelNumber(Point p, int repetitions) {
+        Result start = new Result();
+        start.x = p.x;
+        start.y = p.y;
+        calculateMandelNumber(p, repetitions, start);
+        return start;
+    }
+    
+    protected static void calculateMandelNumber(Point p, int repetitions, Result start) {
+        int n = start.repetitions;
+        
+        while (start.x * start.x + start.y * start.y <= 4 && n <= repetitions) {
+            double new_x = start.x * start.x - start.y * start.y + p.x;
+            start.y = 2 * start.x * start.y + p.y;
+            start.x = new_x;
+            n++;
+        }
+        
+        start.mandelNumber = n;
+    }
+    
+    public static class Point {
+        double x, y;
+        
+        public Point(double x, double y) {
+            this.x = x;
+            this.y = y;
+        }
+        
+        @Override
+        public boolean equals(Object another) {
+            if (another == null || another.getClass() != Point.class) {
+                return false;
+            }
+            Point that = (Point) another;
+            return that.x == x && that.y == y;
+        }
+
+        @Override
+        public int hashCode() {
+            int hash = 7;
+            hash = 97 * hash + (int) (Double.doubleToLongBits(this.x) ^ (Double.doubleToLongBits(this.x) >>> 32));
+            hash = 97 * hash + (int) (Double.doubleToLongBits(this.y) ^ (Double.doubleToLongBits(this.y) >>> 32));
+            return hash;
+        }
+        
+        @Override
+        public String toString() {
+            return String.format("(%f,%f)", x, y);
+        }
+    }
+    
+    protected static class Result {
+        int mandelNumber = -1, repetitions = -1;
+        double x, y;
+    }
+    
+}