Fixed coupling back to coupling rather than phase angle

examples/Coupling.cpp

 
         Kern->SetIntegrationSize( (Vector3r() << 50,100,20).finished() );
         Kern->SetIntegrationOrigin( (Vector3r() << 0,0,0.01).finished() );
-        Kern->SetTolerance( 1e-2 ); // 1e-12
+        Kern->SetTolerance( 1e-12 ); // 1e-12
 
     std::vector<std::string> tx = {std::string("Coil 1")};//,std::string("Coil 2")};
     std::vector<std::string> rx = {std::string("Coil 2")};

src/Coupling.cpp

     //      Method:  f
     //--------------------------------------------------------------------------------------
     Complex Coupling::f( const Vector3r& r, const Real& volume, const Vector3cr& Ht, const Vector3cr& Hr ) {
-        //return volume * ( Ht.dot(Hr) );                              // coupling
+        return volume * ( Ht.dot(Hr) );                              // coupling
         //return volume * (1.-((Ht+Hr).norm()/(Hr.norm() + Ht.norm()))); // interference
-        return volume * std::acos( (Ht.dot(Hr) / (Ht.norm()*Hr.norm())) ); // angle
+        //return volume * std::acos( (Ht.dot(Hr) / (Ht.norm()*Hr.norm())) ); // angle
     }
 
     //--------------------------------------------------------------------------------------