View Compilation Error

0_0_18091303_31490.cpp: In function 'int solve()':
0_0_18091303_31490.cpp:80:46: error: no matching function for call to 'Point::dot(Point)'
       double r = ij.dot(p[i] - p[q[l].second]) / r2;
                                              ^
0_0_18091303_31490.cpp:80:46: note: candidate is:
0_0_18091303_31490.cpp:44:9: note: double Point::dot(Point&)
  double dot(Point& p){ return x*p.x + y*p.y + z*p.z; }
         ^
0_0_18091303_31490.cpp:44:9: note:   no known conversion for argument 1 from 'Point' to 'Point&'