[cilib-devel] [PATCH 2/4] Matrix rotation and determinant.

[Gary P. <gpa...@gm...>]

The current implementation of the rotation and the determinant. These
implementations are restricted to 2-dimensions at the moment. Plans to
extend this to n-dimensions is planned.

Signed-off-by: Gary Pampara <gpa...@gm...>
---
 pom.xml                                            |    5 ----
 .../cilib/type/types/container/Matrix.java         |   23 ++++++++++++++++++++
 .../cilib/type/types/container/MatrixTest.java     |   19 ++++++++++++++++
 3 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/pom.xml b/pom.xml
index bf3b9f4..fcc9dff 100644
--- a/pom.xml
+++ b/pom.xml
@@ -163,11 +163,6 @@
         </configuration>
       </plugin>
       <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.4.2</version>
-      </plugin>
-      <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>javacc-maven-plugin</artifactId>
         <version>2.5</version>
diff --git a/src/main/java/net/sourceforge/cilib/type/types/container/Matrix.java b/src/main/java/net/sourceforge/cilib/type/types/container/Matrix.java
index f42abb6..913ff7f 100644
--- a/src/main/java/net/sourceforge/cilib/type/types/container/Matrix.java
+++ b/src/main/java/net/sourceforge/cilib/type/types/container/Matrix.java
@@ -169,6 +169,29 @@ public final class Matrix implements Type {
     }
 
     /**
+     * 
+     * @param angle The rotation angle defined in radians.
+     * @return
+     */
+    public Matrix rotate(double angle) {
+        Matrix rotation = new Matrix(2, 2);
+        rotation.contents[0][0] = Math.cos(angle);
+        rotation.contents[0][1] = -Math.sin(angle);
+        rotation.contents[1][0] = Math.sin(angle);
+        rotation.contents[1][1] = Math.cos(angle);
+
+        return this.times(rotation);
+    }
+
+    /**
+     * 
+     * @return
+     */
+    public double determinant() {
+        return contents[0][0]*contents[1][1] - contents[1][0]*contents[0][1];
+    }
+
+    /**
      * {@inheritDoc}
      */
     @Override
diff --git a/src/test/java/net/sourceforge/cilib/type/types/container/MatrixTest.java b/src/test/java/net/sourceforge/cilib/type/types/container/MatrixTest.java
index 6144707..0c2c98e 100644
--- a/src/test/java/net/sourceforge/cilib/type/types/container/MatrixTest.java
+++ b/src/test/java/net/sourceforge/cilib/type/types/container/MatrixTest.java
@@ -211,6 +211,25 @@ public class MatrixTest {
         }
     }
 
+    @Test
+    public void rotation() {
+        double angle = Math.PI / 4.0;
+        
+        Matrix matrix = Matrix.builder().rows(2).columns(2).addRow(1.0, 1.0).addRow(1.0, 1.0).build();
+        Matrix result = matrix.rotate(angle);
+
+        Assert.assertThat(result.valueAt(0, 0), is(1.414213562373095));
+        Assert.assertThat(result.valueAt(0, 1), is(1.1102230246251565E-16));
+        Assert.assertThat(result.valueAt(1, 0), is(1.414213562373095));
+        Assert.assertThat(result.valueAt(1, 1), is(1.1102230246251565E-16));
+    }
+
+    @Test
+    public void determinant() {
+        Matrix matrix = Matrix.builder().rows(2).columns(2).addRow(1.0, 1.0).addRow(1.0, 1.0).build();
+        Assert.assertThat(matrix.determinant(), is(0.0));
+    }
+
     @Test(expected=IllegalStateException.class)
     public void invalidIdentity() {
         Matrix.builder().rows(2).columns(5).identity().build();
-- 
1.6.4