// test_matrix.cpp  dynamic matrix,  just vector of vectors

#include <vector>
#include <iostream>
using namespace std;

int main()
{
  typedef vector<double> d_vec;
  typedef vector<d_vec>  d_mat;

  d_mat mat; // dynamic size matrix, initially  0 by 0
  d_vec row;

  cout << "test_matrix.cpp" << endl;

  row.push_back(1.0);
  row.push_back(2.0);
  row.push_back(3.0);  // build the first row
  mat.push_back(row);
  row[0]=4.0;
  mat.push_back(row);
  row[1]=5.0;
  mat.push_back(row); // now have 3 by 3  1.0  2.0  3.0
                      //                  4.0  2.0  3.0
                      //                  4.0  5.0  3.0

  cout << "mat[2][2]=" << mat[2][2] << endl;
  mat[1][1]=9.0;

  mat[0].push_back(4.0);
  mat[1].push_back(6.0);
  mat[2].push_back(7.0);
  row.push_back(8.0);
  mat.push_back(row); // now have 4 by 4  1.0  2.0  3.0  4.0
                      //                  4.0  9.0  3.0  6.0
                      //                  4.0  5.0  3.0  7.0
                      //                  4.0  5.0  3.0  8.0

  cout << "mat[2][3]=" << mat[2][3] << endl;
  mat[2][3]=7.0001;

  // obviously do not use  mat[4][4], it does not exists

  for(int i=0; i<mat.size(); i++)
    for(int j=0; j<mat[i].size(); j++)
      cout << "mat[" << i << "][" << j << "]= " << mat[i][j] << endl;

  return 0;
}