Modified Array Class tutorial, added examples

doc/examples/Tutorial_ArrayClass_accessing.cpp

@@ -0,0 +1,24 @@
+#include <Eigen/Dense>
+#include <iostream>
+
+using namespace Eigen;
+using namespace std;
+
+int main()
+{
+  ArrayXXf  m(2,2);
+  
+  //assign some values coefficient by coefficient
+  m(0,0) = 1.0; m(0,1) = 2.0;
+  m(1,0) = 3.0; m(1,1) = 4.0;
+  
+  //print values to standard output
+  cout << m << endl << endl;
+ 
+  // using the comma-initializer is also allowed
+  m << 1.0,2.0,
+       3.0,4.0;
+     
+  //print values to standard output
+  cout << m << endl;
+}