/* A program that prints the transpose of a given matrix.
   Task: compute the trace of a matrix i.e. sum of the diagonal    entries of a matrix.
   Task: Frobenius product of two matrices A and B:  i.e. trace of the matrix A*transpose(B).
   
*/
#include <iostream>
using namespace std;


double trace( double A[2][2] ) 
   {
     double trace = 0.0;
      for (unsigned int i =0 ; i < 2 ; ++i) 
     {
	trace += A[i][i]; 
    
      }//for-i

return trace ;
 } //end of the trace function.

int main() {
    double A[2][2] ={ {1,2},{3,4} } ;
  cout<< "The trace is: "<< trace (A)<< endl; 
 
    return 0;
}