Hello everyone,

So firstly, I'm using version 8.3.0. If this is a real bug but has been 
addressed in a newer version please let me know, but I have not found any 
info about it in the change logs up to version 8.4.2 or the user group.

I'm using a block matrix to solve a steady, variable density Navier-Stokes 
system in parallel (an extension of step-32). Rather than approximate the 
Schur complement term as the pressure mass matrix, I'm approximating it as 
the matrix BG, where B is the continuity matrix sub-block and G is the 
pressure gradient sub-block. So the full Schur complement term is B A^-1 G 
~ BG. B and G are non-square matrices, and BG should be a square matrix 
that has the same size as the pressure mass matrix.

In serial, this works just fine and everything goes smoothly. In parallel, 
if I export B and G and multiply them (I used Mathematica), I also get the 
correct BG matrix. However, when I use 
TrilinosWrappers::SparseMatrix::mmult in parallel, something goes wrong and 
the resulting matrix is incorrect (not even square). I've attached 
Mathematica's view of the correct BG matrix from mmult in serial and also 
the BG matrix from mmult using 2 processors in parallel.

Any help would be greatly appreciated.

Ben Shields

The deal.II project is located at http://www.dealii.org/
For mailing list/forum options, see 
You received this message because you are subscribed to the Google Groups 
"deal.II User Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to dealii+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Attachment: BG_serial.pdf
Description: Adobe PDF document

Attachment: BG_parallel.pdf
Description: Adobe PDF document

Reply via email to