Open qiongsiwu opened 5 years ago
We will talk about this general trick next class but this is ensuring that the hessian for Newton’s method is positive definite. This guarantees that the newton search direction is, locally, a descent direction and helps make the solver more robust.
Thanks for asking this, it’s a great question.
As an aside, I wanted to provide the code for these little tricks since I figure everyone already has enough to implement in this class :) but I can add a comment to the source code to make it less opaque.
After calling
quadrature_single_point
, the code constructs a solver, computes some eigenvalues and eigen vectors, and reassignsH
.What is this code doing? I am not sure where in the notes/lecture this was discussed. Help/pointers are appreciated!
https://github.com/dilevin/CSC2549-a3-finite-elements-3d/blob/98c2e373e8a5c779da31eb7106a2c40530a98fea/src/d2V_linear_tetrahedron_dq2.cpp#L17-L29