11-32.cpp

#include "matrix.hpp" // recipe 11.13
#include "kmatrix.hpp" // recipe 11.14
#include <iostream>
#include <cassert>

using namespace std;

template<class M1, class M2, class M3>
void matrixMultiply(const M1& m1, const M2& m2, M3& m3)
{
  assert(m1.cols( ) == m2.rows( ));
  assert(m1.rows( ) == m3.rows( ));
  assert(m2.cols( ) == m3.cols( ));
  for (int i=m1.rows( )-1; i >= 0; --i) {
    for (int j=m2.cols( )-1; j >= 0; --j) {
      for (int k = m1.cols( )-1; k >= 0; --k) {
        m3[i][j] += m1[i][k] * m2[k][j];
      }
    }
  }
}

int main( )
{
  matrix<int> m1(2, 1);
  matrix<int> m2(1, 2);
  kmatrix<int, 2, 2> m3;
  m3 = 0;
  m1[0][0] = 1; m1[1][0] = 2;
  m2[0][0] = 3; m2[0][1] = 4;
  matrixMultiply(m1, m2, m3);
  cout << "(" << m3[0][0] << ", " << m3[0][1] << ")" << endl;
  cout << "(" << m3[1][0] << ", " << m3[1][1] << ")" << endl;
}