#include <iostream.h>

class Vector
{
public:
   float x[4];
};


class Matrix
{
public:
   virtual Vector operator*(Vector &);
};

class DenseMatrix : public Matrix
{
public:
   float A[4][4];

   virtual Vector operator*(Vector &v)
   {
      Vector z;
      int i, j;

      for (i = 0; i < 4; i=i+1)
         z.x[i] = 0;

      for (i = 0; i < 4; i=i+1)
         for (j = 0; j < 4; j=j+1)
            z.x[i] = z.x[i] + A[i][j]*v.x[j];

      return z;
   }
};


class SparseMatrix : public Matrix
{
public:
   float A[5];
   int row[5];
   int col[5];

   virtual Vector operator*(Vector &v)
   {
      Vector z;
      int i, j;

      for (i = 0; i < 4; i=i+1)
         z.x[i] = 0;

      for (i = 0; i < 4; i=i+1)
         for (j = 0; j < 4; j=j+1)
            z.x[i] = z.x[i] + A[i][j]*v.x[j];

      return z;
   }
};


int main(int argc, char *argv[])
{
   DenseMatrix M;
   Matrix *X;
   Vector v1, v2;
   int i, j;

   for (i = 0; i < 4; i = i + 1)
      for (j = 0; j < 4; j = j + 1)
	 M.A[i][j] = i + j;

   for (i = 0; i < 4; i = i + 1)
      v1.x[i] = i + 100;

   X = &M;
   v2 = (*X) * v1;

   cout << "Matrix M:" << endl;
   for (i = 0; i < 4; i = i + 1)
   {
      for (j = 0; j < 4; j = j + 1)
	 cout << M.A[i][j] << "\t";
      cout << "\n";
   }
   cout << "\n";

   cout << "Vector v1:" << endl;
   for (i = 0; i < 4; i = i + 1)
      cout << v1.x[i] << "\t";
   cout << "\n\n";

   cout << "Vector v2:" << endl;
   for (i = 0; i < 4; i = i + 1)
      cout << v2.x[i] << "\t";
   cout << "\n\n";
}