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.
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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