From 01ae0fb9bd655662df585895f3a2f608da96e13a Mon Sep 17 00:00:00 2001
From: Fabian Becker <halfdan@xnorfz.de>
Date: Sat, 20 Dec 2014 13:26:59 +0100
Subject: [PATCH] Added Zakharov problem

---
 src/eva2/problems/F23Problem.java |  4 --
 src/eva2/problems/F24Problem.java | 76 +++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 4 deletions(-)
 create mode 100644 src/eva2/problems/F24Problem.java

diff --git a/src/eva2/problems/F23Problem.java b/src/eva2/problems/F23Problem.java
index b1f2d46f..28f11677 100644
--- a/src/eva2/problems/F23Problem.java
+++ b/src/eva2/problems/F23Problem.java
@@ -78,10 +78,6 @@ public class F23Problem extends AbstractProblemDoubleOffset implements Interface
         return sb.toString();
     }
 
-    /**
-     * These are for GUI
-     */
-
     /**
      * This method allows the CommonJavaObjectEditorPanel to read the
      * name to the current object.
diff --git a/src/eva2/problems/F24Problem.java b/src/eva2/problems/F24Problem.java
new file mode 100644
index 00000000..ff253179
--- /dev/null
+++ b/src/eva2/problems/F24Problem.java
@@ -0,0 +1,76 @@
+package eva2.problems;
+
+import eva2.tools.math.Mathematics;
+import eva2.util.annotation.Description;
+
+/**
+ * Zakharov function
+ */
+@Description("Zakharov function")
+public class F24Problem extends AbstractProblemDoubleOffset implements InterfaceHasInitRange {
+    private double initialRangeRatio = 1.; // reduce to initialize in a smaller subrange of the original range (in the corner box)
+
+    public F24Problem() {
+        super();
+        setDefaultRange(10);
+    }
+
+    public F24Problem(F24Problem b) {
+        super();
+        super.cloneObjects(b);
+    }
+
+    public F24Problem(int dim) {
+        super(dim);
+    }
+
+    public F24Problem(int dim, double defRange) {
+        this(dim);
+        setDefaultRange(defRange);
+    }
+
+    /**
+     * This method returns a deep clone of the problem.
+     *
+     * @return the clone
+     */
+    @Override
+    public Object clone() {
+        return new F24Problem(this);
+    }
+
+    @Override
+    public double[] evaluate(double[] x) {
+        double sum1 = 0.0, sum2 = 0.0, sum3 = 0.0;
+
+        for (int i = 0; i < x.length; i++) {
+            sum1 += Math.pow(x[i], 2);
+            sum2 += Math.pow(0.5 * i * Math.pow(x[i], 2), 2);
+            sum3 += Math.pow(0.5 * i * Math.pow(x[i], 2), 4);
+        }
+
+        return new double[] {sum1 + sum2 + sum3};
+    }
+
+    @Override
+    public String getName() {
+        return "Zakharov";
+    }
+
+    @Override
+    public Object getInitializationRange() {
+        if (initialRangeRatio < 1.) {
+            double[][] gR = makeRange();
+            double[][] initR = makeRange();
+            Mathematics.scaleRange(initialRangeRatio, initR);
+            for (int i = 0; i < getProblemDimension(); i++) {
+                double d = gR[i][0] - initR[i][0];
+                initR[i][0] += d; // shift back by original offsets
+                initR[i][1] += d;
+            }
+            return initR;
+        } else {
+            return makeRange();
+        }
+    }
+}