// -*- c++ -*-
//
// $COPYRIGHT$
//
//===========================================================================

#include "mtl/matrix.h"
#include "mtl/mtl.h"
#include "mtl/utils.h" 

/*
  Swaps the first row with the row that has the largest element in
  column 1. This is the kind of operation one would do inside a
  Gaussian elimintation algorithm.

  Sample Output

  3x3
  [
  [1,1.5,4.5],
  [3,2.5,9.5],
  [2,3.5,5.5]
  ]
  3x3
  [
  [3,2.5,9.5],
  [1,1.5,4.5],
  [2,3.5,5.5]
  ]

 */

using namespace mtl;
using namespace std;

int
main()
{
  //begin
  typedef matrix< double,
                  rectangle<>, 
                  dense<external>,
                  column_major>::type Matrix; 
  const Matrix::size_type N = 3;
  Matrix::size_type large;
  double dA[] = { 1, 3, 2, 1.5, 2.5, 3.5, 4.5, 9.5, 5.5 };
  Matrix A(dA, N, N);
  //end
  print_all_matrix(A);
  //begin
  //  Find the largest element in the first column.
  large = max_index(A[0]);
  //end
  cout << "x" << endl;
  //begin
  // Swap the first row with the row containing the largest
  // element in the first column.
  swap( rows(A)[0] , rows(A)[large]);
  //end
  print_all_matrix(A);

  return 0;
}