#ifndef _matrix_h_
#define _matrix_h_

#include <iostream>
using namespace std;


template <typename ValType>
class  Matrix;

template <typename ValType>
ostream & operator << (ostream & os, Matrix<ValType> & mat);

template <typename ValType>
class  Matrix
{
public:
  Matrix(int nrows, int ncols);
  int num_rows();
  int num_cols();
 
  virtual ValType & operator()(int i, int j) = 0; 

protected:  
  int _nrows, _ncols;
};

template <typename ValType>
int Matrix<ValType>::num_rows()
{
  return _nrows;
}

template <typename ValType>
int Matrix<ValType>::num_cols()
{
  return _ncols;
}

template <typename ValType>
Matrix<ValType>::Matrix(int nrows, int ncols)
{
  _nrows = nrows;
  _ncols = ncols;
}


template <typename ValType>
ostream & operator << (ostream & os, Matrix<ValType> & mat)
{
  for (int i = 0; i < mat.num_rows(); i++)
  {
    for (int j = 0; j < mat.num_cols(); j++)
      os << mat(i, j) << '\t';
    os << endl;
  }
  return os;
}


#endif