added test for identity matrix

schleichardt · Apr 12, 2012 · 3ba00bb · 3ba00bb
1 parent 811053b
commit 3ba00bb
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 1 deletion.
diff --git a/src/main/scala/info/schleichardt/math/ValueMatrix.scala b/src/main/scala/info/schleichardt/math/ValueMatrix.scala
@@ -5,6 +5,18 @@ import collection.immutable.IndexedSeq
 
 object ValueMatrix {
   def apply(input: Seq[Double]*) = new ValueMatrix(input)
+  def identityMatrixForSize(size: Int) = {
+    val seq: Seq[Seq[Double]] =
+      for (line <- 0 until size) yield {
+        for (column <- 0 until size) yield {
+          if (line == column)
+            1.0
+          else
+            0.0
+        }
+      }
+    new ValueMatrix(seq)
+  }
 }
 
 class ValueMatrix(val content: Seq[Seq[Double]]) {
@@ -79,4 +91,6 @@ class ValueMatrix(val content: Seq[Seq[Double]]) {
       }
     new ValueMatrix(seq)
   }
+
+  lazy val isIdentityMatrix: Boolean = columnCount == content.length && ValueMatrix.identityMatrixForSize(columnCount) == this
 }
diff --git a/src/test/scala/MatrixSpec.scala b/src/test/scala/MatrixSpec.scala
@@ -33,6 +33,11 @@ class MatrixSpec extends Specification with JUnit with ScalaTest {
       matrixWith3Rows * matrixWith2Rows must throwA[IllegalArgumentException]
       matrixWith2Rows * matrixWith3Rows must not(throwA[IllegalArgumentException])
     }
-
+    "can be a identity matrix" in {
+      val identityMatrix = ValueMatrix(Seq(1, 0, 0), Seq(0, 1, 0), Seq(0, 0, 1))
+      val notIdentityMatrix = ValueMatrix(Seq(1, 0, 0), Seq(0, 1, 0), Seq(0, 1, 0))
+      identityMatrix.isIdentityMatrix must be_==(true)
+      notIdentityMatrix.isIdentityMatrix must be_==(false)
+    }
   }
 }