1 better hexa_volume for divergence load:
2 replace decomposition in tetras by jacobian or base times average height
5 decide using A not just geometry
6 horizontal semicoarsening for large A(3,3)
8 horizontal semicoarsening based on dx=dy, make explicit
9 make sure there is some semicoarsening, horizontal or vertical
11 comments in hexa_coupling.m and hexa_coupling_test.m
14 sparse assembly 3 functionalities
15 apply_boundary_conditions to K and F separately - done
16 apply_boundary_conditions to fortran
17 explain variational multigrid in notes
18 cycling logic in fortran
19 coarsest level without direct solve