// Second try to make member function as friend

#include <iostream.h>

class Vector3;

class Matrix3x3
{
private:
   double A[3][3];

public:
   Vector3  operator* ( Vector3 & v )          
   {
      Vector3 out;
      int i, k;

      for (i = 0; i < 3; i = i + 1)
      {
         out.d[i] = 0.0;

         for (k = 0; k < 3; k = k + 1)
            out.d[i] = out.d[i] +  A[i][k] * v.d[k];               
      }

      return(out);
   }
};

class Vector3
{
private:
   double d[3];       

   friend Vector3  Matrix3x3::operator* ( Vector3 & v );
};