Modified Array Class tutorial, added examples

doc/examples/Tutorial_ArrayClass_mult.cpp

@@ -0,0 +1,20 @@
+#include <Eigen/Dense>
+#include <iostream>
+
+using namespace Eigen;
+using namespace std;
+
+int main()
+{
+  ArrayXXf a(2,2);
+  ArrayXXf b(2,2);
+  
+  a << 1,2,
+       3,4;
+
+  b << 5,6,
+       7,8;
+
+  cout << "a * b = " << endl
+       << a * b << endl;
+}