Reductions/Broadcasting/Visitor Tutorial added

doc/examples/Tutorial_ReductionsVisitorsBroadcasting_maxnorm.cpp

@@ -0,0 +1,19 @@
+#include <iostream>
+#include <Eigen/Dense>
+
+using namespace std;
+int main()
+{
+  Eigen::MatrixXf mat(2,4);
+  mat << 1, 2, 6, 9,
+         3, 1, 7, 2;
+  
+  int   maxIndex;
+  float maxNorm = mat.colwise().sum().maxCoeff(&maxIndex);
+  
+  std::cout << "Maximum sum at position " << maxIndex << std::endl;
+
+  std::cout << "The corresponding vector is: " << std::endl;
+  std::cout << mat.col( maxIndex ) << std::endl;
+  std::cout << "And its sum is is: " << maxNorm << std::endl;
+}