Dr. Baker, I'm working through Lab 12, and I'm not quite sure how to properly convert the GWS code to a TWS, unfortunately it seems that the video lecture labled as dealing with Lab 12 actually has you going over Lab 13. I took the liberty of sending this through the listserv as your answer can benefit the whole class Based on pseudo code in the problem statement, I put together this code to add onto the 'Equations for Set 0' where h is h = (right_X - left_X)/mesh where mesh is 10,20,40,80 Orginal GWS code+... +asres2D((h^2)*Pe/12,[ ],[ ],-1,'B211L',q)... +asres2D((h^2)*Pe/12,[ ],[ ],-1,'B212L',q)... +asres2D((h^2)*Pe/12,[ ],[ ],-1,'B221L',q)... +asres2D((h^2)*Pe/12,[ ],[ ],-1,'B222L',q); I'm not sure how I miss-implemented the TWS solution, other than perhaps not adding in something in the jacobian portion? Thank you Spero Peters