More Math tests

refs #53

src/main/java/eva2/tools/math/Mathematics.java

@@ -389,8 +389,8 @@ public final class Mathematics {
     /**
      * Intersect two ranges resulting in the maximum range contained in both.
      *
-     * @param modRange
-     * @param makeRange
+     * @param r1
+     * @param r2
      * @param destRange
      */
     public static void intersectRange(double[][] r1, double[][] r2,
@@ -538,6 +538,8 @@ public final class Mathematics {
     }
 
     /**
+     * Linear interpolation between two points
+     *
      * @param f0
      * @param f1
      * @param t
@@ -553,7 +555,7 @@ public final class Mathematics {
      *
      * @param x  The argument at the point with unknown function value
      * @param x0 The argument at the last position with a function value
-     * @param x1 The argument at the next known fuction value
+     * @param x1 The argument at the next known function value
      * @param f0 The function value at the position x0
      * @param f1 The function value at the position x1
      * @return The function value at position x given by linear interpolation.
@@ -1214,9 +1216,7 @@ public final class Mathematics {
      */
     public static double[] svDiv(double s, double[] v) {
         double[] res = new double[v.length];
-        for (int i = 0; i < v.length; i++) {
-            res[i] = v[i] / s;
-        }
+        svDiv(s, v, res);
         return res;
     }
 
@@ -1243,9 +1243,7 @@ public final class Mathematics {
      */
     public static double[] svMult(double s, double[] v) {
         double[] res = new double[v.length];
-        for (int i = 0; i < v.length; i++) {
-            res[i] = v[i] * s;
-        }
+        svMult(s, v, res);
         return res;
     }
 
@@ -1254,7 +1252,6 @@ public final class Mathematics {
      *
      * @param s a scalar
      * @param v an array to be multiplied with s.
-     * @return a scaled array.
      */
     public static void svMult(double s, double[] v, double[] res) {
         for (int i = 0; i < v.length; i++) {
@@ -1265,7 +1262,7 @@ public final class Mathematics {
     /**
      * Add vectors scaled: res[i] = s*v[i] + w[i]
      *
-     * @param s
+     * @param s Scaling factor
      * @param v
      * @param w
      * @return

src/test/java/eva2/tools/math/MathematicsTest.java

@@ -4,9 +4,7 @@ import org.junit.Test;
 
 import java.util.Arrays;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 public class MathematicsTest {
 
@@ -45,6 +43,8 @@ public class MathematicsTest {
     @Test
     public void testContains() throws Exception {
         assertTrue(Mathematics.contains(new int[]{1, 2, 3, 4, 5}, 4));
+
+        assertFalse(Mathematics.contains(new int[]{1, 2, 3, 4, 5}, 9));
     }
 
     @Test
@@ -145,7 +145,9 @@ public class MathematicsTest {
 
     @Test
     public void testScale() throws Exception {
-
+        double[] values = {1.0, 2.0, 3.0};
+        Mathematics.scale(2, values);
+        assertArrayEquals(new double[]{2.0, 4.0, 6.0}, values, 0.0);
     }
 
     @Test
@@ -175,5 +177,53 @@ public class MathematicsTest {
         assertFalse(Mathematics.isInRange(new double[]{9.9, 2.2}, ranges));
     }
 
+    @Test
+    public void testInverse() throws Exception {
+        double[][] matrix = {{4.0, 3.0}, {3.0, 2.0}};
+        double[][] inverseMatrix = {{-2.0, 3.0}, {3.0, -4.0}};
 
+        double[][] result = Mathematics.inverse(matrix);
+        for (int i = 0; i < result.length; i++) {
+            assertArrayEquals(inverseMatrix[i], result[i], 0.0);
+        }
+
+        // Non square matrix
+        assertNull(Mathematics.inverse(new double[][]{{1.0, 2.0}}));
+
+        // Null matrix
+        assertNull(Mathematics.inverse(null));
+
+        // Matrix with determinant = 0
+        assertNull(Mathematics.inverse(new double[][]{
+                {1.0, 4.0, 5.0},
+                {2.0, 5.0, 7.0},
+                {3.0, 6.0, 9.0}
+        }));
+    }
+
+    @Test
+    public void testDeterminant() throws Exception {
+        // 3x3 Matrix with determinant 0
+        assertEquals(0.0, Mathematics.determinant(new double[][]{
+                {1.0, 4.0, 5.0},
+                {2.0, 5.0, 7.0},
+                {3.0, 6.0, 9.0}
+        }), 0.0);
+    }
+
+    @Test
+    public void testLinearInterpolation() throws Exception {
+        // Find x = 2.0 for x0(1,1) and x1(3,3)
+        assertEquals(2.0, Mathematics.linearInterpolation(2.0, 1.0, 3.0, 1.0, 3.0), 0.0);
+
+        // If x0 and x1 are the same we can't interpolate (returns f0)
+        assertEquals(3.0, Mathematics.linearInterpolation(3.0, 2.0, 2.0, 3.0, 3.0), 0.0);
+    }
+
+    @Test
+    public void testVvSub() throws Exception {
+        double[] v1 = {5.0, 6.0, 7.0}, v2 = {3.0, 4.0, 5.0};
+
+        assertArrayEquals(new double[]{2.0, 2.0, 2.0}, Mathematics.vvSub(v1, v2), 0.0);
+    }
 }