Dear all,

I am trying to adapt the systems_of_equations_ex7.C to heterogeneous
Dirichlet BC, and I seem to hit a few challenges. Could you please help me
out here?

1) My first attempt is simply adding the heterogeneous BC like a linear
problem and used
`dof_map.heterogenously_constrain_element_matrix_and_vector (Ke, Fe,
dof_indices)` instead of the `dof_map.constrain_element_matrix_and_vector
(Ke, Fe, dof_indices)` in the jacobian() function. Note that I did NOT
have `system.rhs->add_vector (Fe, dof_indices)` in the jacobian() function.
The solution seems to be slightly wrong - in the result file, some nodes
did not have the right prescribed displacements, although their neighboring
nodes seemed correct. Then I added the `system.rhs->add_vector (Fe,
dof_indices)` in the jacobian() function then the results diverged.

2) I noticed that the BCs have to be applied before the es.init(). However,
for NonlinearImplicitSystem we may want to divide the solution into
multiple steps and we'd then need to update the heterogeneous BC per step.
Would this be possible?

Thank you!

Best,
Shawn

-- 
Yuxiang "Shawn" Wang, PhD
yw...@virginia.edu
+1 (434) 284-0836

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