Wasim,
I am working on a problem very similar to the Laplace equation solved in
step-3. I have made some changes to step-3 as I need to. Now, I want to solve
this problem in parallel. I looked at step-40, which solves the Laplace
equation in parallel. However, it uses a constraints object to apply BCs.
Right now, I don't have any hanging nodes to handle, so I used a std::map
object to apply BCs. I first copy all the local contributions to the global
matrix and then apply the BCs.
While going through the documentation of step-40, I read that *"Copying
local contributions into the global matrix must include distributing
constraints and boundary values. In other words, we cannot (as we did in
step-6
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dealii.org%2Fcurrent%2Fdoxygen%2Fdeal.II%2Fstep_6.html&data=05%7C01%7CWolfgang.Bangerth%40colostate.edu%7C4d743ade451748dc8de008db0eca03a4%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638120033038833445%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=jiwhUoR2e3pdMgrBUuE0O6aNkvqizuqsxrb61F8YmUE%3D&reserved=0>) first copy every local contribution into the global matrix and only in a later step take care of hanging node constraints and boundary values."*
*
*
This text turns out to no longer be correct. It refers to a method step-6 used
to use, but no longer does. I've fixed this here:
https://github.com/dealii/dealii/pull/14801/files
If my understanding is correct, then I think the following line of code does
this job in step-40:
*constraints.distribute_local_to_global(cell_matrix,cell_rhs,local_dof_indices,*
**
*system_matrix,system_rhs);*
My doubt is whether it is possible to do this(*Copying local contributions
into the global matrix and distributing boundary values.*) with the std::map
object or do I need to use a constraint object even though I don't have any
hanging nodes to handle.
It requires an AffineConstraints object, just like the current state of step-6
and step-40 do.
Best
W.
--
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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