Fixed some ml test cases

test/zutil/math/MatrixTest.java

@@ -106,8 +106,11 @@ public class MatrixTest {
     @Test
     public void vectorMultiply(){
         assertArrayEquals(
-                new double[][]{{8},{14}},
-                Matrix.multiply(new double[][]{{2,3},{-4,9}}, new double[]{1,2}));
+                new double[]{1.4, 1.9, 2.4, 2.9},
+                Matrix.multiply(
+                        new double[][]{{1, 2, 3}, {1, 3, 4}, {1, 4, 5}, {1, 5, 6}},
+                        new double[]{0.1, 0.2, 0.3}),
+                0.001);
     }
 
     @Test

test/zutil/ml/LinearRegressionTest.java

@@ -12,12 +12,12 @@ public class LinearRegressionTest {
 
     @Test
     public void calculateHypotesis() {
-        double[][] hypotesis = LinearRegression.calculateHypotesis(
-                /* x */ new double[][]{{1, 2}, {1, 3}, {1, 4}, {1, 5}},
-                /* theta */ new double[]{0.1, 0.2}
+        double[] hypotesis = LinearRegression.calculateHypothesis(
+                /* x */ new double[][]{{1, 2, 3}, {1, 3, 4}, {1, 4, 5}, {1, 5, 6}},
+                /* theta */ new double[]{0.1, 0.2, 0.3}
         );
 
-        assertArrayEquals(new double[][]{{0.5}, {0.7}, {0.9}, {1.1}}, hypotesis);
+        assertArrayEquals(new double[]{1.4, 1.9, 2.4, 2.9}, hypotesis, 0.001);
     }
 
     @Test
@@ -33,7 +33,7 @@ public class LinearRegressionTest {
 
     @Test
     public void gradientAscent() {
-        double[] theta = LinearRegression.gradientAscent(
+        double[] theta = LinearRegression.gradientDescent( // one iteration
                 /* x */ new double[][]{{1, 5},{1, 2},{1, 4},{1, 5}},
                 /* y */ new double[]{1, 6, 4, 2},
                 /* theta */ new double[]{0, 0},

test/zutil/test/ZutilAssert.java

@@ -0,0 +1,47 @@
+package zutil.test;
+
+import org.junit.Assert;
+import org.junit.internal.ArrayComparisonFailure;
+import org.junit.internal.InexactComparisonCriteria;
+
+/**
+ * Some additional assert functions that are missing from JUnit
+ */
+public class ZutilAssert extends Assert {
+
+    private ZutilAssert() {}
+
+    /**
+     * Asserts that two short arrays are equal. If they are not, an
+     * {@link AssertionError} is thrown.
+     *
+     * @param   expected   double array with expected values.
+     * @param   actual     double array with actual values
+     */
+    public static void assertArrayEquals(double[][] expected, double[][] actual, double delta) {
+        ZutilAssert.assertArrayEquals(null, expected, actual, delta);
+    }
+
+    /**
+     * Asserts that two int arrays are equal. If they are not, an
+     * {@link AssertionError} is thrown with the given message.
+     *
+     * @param   message   the identifying message for the {@link AssertionError} (<code>null</code>
+     * okay)
+     * @param   expected  double array with expected values.
+     * @param   actual    double array with actual values
+     */
+    public static void assertArrayEquals(String message, double[][] expected,
+                                         double[][] actual, double delta) throws ArrayComparisonFailure {
+        // If both arrays are referencing the same object or null
+        if (expected == actual)
+            return;
+
+        // Check array lengths
+        if (expected.length != actual.length)
+            fail(message + ". The array lengths of the first dimensions do not match.");
+
+        // Check all sub arrays
+        new InexactComparisonCriteria(delta).arrayEquals(message, expected, actual);
+    }
+}