Professor Bangerth - Thank you for your reply, however, I just seemed to have solved my problem. I had a block system with one vector valued field and one scalar valued field. When I extract the constant modes for the vector valued field it is very fast (using the vector component mask). However, the same operation for the scalar valued field does not perform quickly. I see that simply omitting this step for the scalar valued field has almost no effect on the solution of the scalar valued problem. Therefore I no longer have any issue :)
Thank you again for your reply and sorry for taking your time. Jonathan On Friday, January 24, 2020 at 12:49:34 PM UTC-5, Wolfgang Bangerth wrote: > > On 1/23/20 5:00 PM, Jonathan Russ wrote: > > > > I noticed that the Trilinos ML preconditioner accessed through the > > TrilinosWrappers benefits heavily from supplying the constant modes or > > the null-space of the laplace operator. Using the extract_constant_modes > > functionality I notice that this can take quite a bit of time for a > > vector valued problem (with 135,000 dofs on 30 processors this took > > about 7 minutes). I was wondering if there is some way for me to speed > > this calculation up somehow? What affects the calculation the most > > (should I not reorder the dofs, etc)? > > Jonathan -- interesting. We do this in most of our codes, and it has > never come up as a problem. Do you think you could construct a minimal > example that shows this? Just set up a DoFHandler and call > extract_constant_modes(). > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > <javascript:> > www: http://www.math.colostate.edu/~bangerth/ > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/cb642c55-42ee-4305-81f9-d29b67362c15%40googlegroups.com.
