From 3df20257b0366ae60c6d498d8479ff9075f00cae Mon Sep 17 00:00:00 2001
From: Ziver Koc <ziver@koc.se>
Date: Thu, 11 Jan 2018 16:35:33 +0100
Subject: [PATCH] Added multiply by element function

---
 src/zutil/math/MatrixMath.java      | 18 ++++++++++++++++++
 test/zutil/math/MatrixMathTest.java |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/src/zutil/math/MatrixMath.java b/src/zutil/math/MatrixMath.java
index 5ad4e10..0c09a43 100755
--- a/src/zutil/math/MatrixMath.java
+++ b/src/zutil/math/MatrixMath.java
@@ -110,6 +110,24 @@ public class MatrixMath {
         return result;
     }
 
+    /**
+     * Element multiplication, each element in matrix1 will be
+     * multiplied with the corresponding element in matrix2.
+     *
+     * @return a new matrix with the result
+     */
+    public static double[][] elemMultiply(double[][] matrix1, double[][] matrix2){
+        elementalPreCheck(matrix1, matrix2);
+        double[][] result = new double[matrix1.length][matrix1[0].length];
+
+        for (int y=0; y < matrix1.length; ++y) {
+            for (int x=0; x < matrix1[y].length; ++x){
+                result[y][x] = matrix1[y][x] * matrix2[y][x];
+            }
+        }
+        return result;
+    }
+
     private static void elementalPreCheck(double[][] matrix1, double[][] matrix2) {
         if (matrix1.length != matrix2.length || matrix1[0].length != matrix2[0].length)
             throw new IllegalArgumentException("Matrices need to be of same dimension: " +
diff --git a/test/zutil/math/MatrixMathTest.java b/test/zutil/math/MatrixMathTest.java
index 193019f..2c2285c 100755
--- a/test/zutil/math/MatrixMathTest.java
+++ b/test/zutil/math/MatrixMathTest.java
@@ -47,6 +47,12 @@ public class MatrixMathTest {
                 MatrixMath.subtract(new double[][]{{2,3},{-4,9}}, new double[][]{{1,2},{3,4}}));
     }
 
+    @Test
+    public void elementalMultiply(){
+        assertArrayEquals(new double[][]{{2,6},{-12,36}},
+                MatrixMath.elemMultiply(new double[][]{{2,3},{-4,9}}, new double[][]{{1,2},{3,4}}));
+    }
+
 
 
     @Test