View Compilation Error

0_0_16972667_21816.cpp: In function 'double calcDis(Point3*, Point3, Plane)':
0_0_16972667_21816.cpp:118:48: error: 'Dot' was not declared in this scope
     return fabs(Dot(pp - p[f.v[0]], f.normal(p))) / f.normal(p).abs();
                                                ^