1 files changed, 55 insertions, 0 deletions
diff --git a/src/main/scala/sims/math/Matrix22.scala b/src/main/scala/sims/math/Matrix22.scala
new file mode 100644
index 0000000..54d24c7
--- /dev/null
+++ b/src/main/scala/sims/math/Matrix22.scala
@@ -0,0 +1,55 @@
+/*
+ * Simple Mechanics Simulator (SiMS)
+ * copyright (c) 2009 Jakob Odersky
+ * made available under the MIT License
+*/
+
+package sims.math
+
+import sims.geometry._
+
+/**A 2x2 matrix.
+ * @param c11 component 1,1
+ * @param c12 component 1,2
+ * @param c21 component 2,1
+ * @param c22 component 2,2
+ */
+case class Matrix22(c11: Double, c12: Double, c21: Double, c22: Double) {
+  
+  /**A 2x2 matrix can be created with two 2D vectors. In this case, each column is represented by a vector.
+   * @param c1 first column
+   * @param c2 second column*/
+  def this(c1: Vector2D, c2: Vector2D) = this(c1.x, c2.x, c1.y, c2.y)
+  
+  /**Determinant of this matrix.*/
+  def det = c11 * c22 - c21 * c12
+  
+  /**Addition.*/
+  def +(m: Matrix22) =
+    new Matrix22(c11 + m.c11, c12 + m.c12,
+                 c21 + m.c21, c22 + m.c22)
+  
+  /**Scalar multiplication.*/
+  def *(n: Double) = 
+    new Matrix22(c11 * n, c12 * n,
+                 c21 * n, c22 * n)
+  
+  /**Matrix multiplication.*/
+  def *(m: Matrix22) = 
+    new Matrix22(c11 * m.c11 + c12 * m.c21, c11 * m.c12 + c12 * m.c22,
+                 c21 * m.c11 + c22 * m.c21, c21 * m.c12 + c22 * m.c22)
+  
+  /**Multiplikation with a 2D vector.*/
+  def *(v: Vector2D) =
+    new Vector2D(c11 * v.x + c12 * v.y,
+                 c21 * v.x + c22 * v.y)
+  
+  /**Inverse.*/
+  def invert = 
+    new Matrix22(c22 / det, -c12 / det,
+                 -c21 / det, c11 / det)
+  }
+
+object Matrix22 {
+  def apply(c1: Vector2D, c2: Vector2D) = new Matrix22(c1.x, c2.x, c1.y, c2.y)
+}