[petsc-users] GAMG with more than one DOF

[David Scott]

On 12/12/2014 16:07, Matthew Knepley wrote:
> On Fri, Dec 12, 2014 at 8:58 AM, David Scott <d.scott at ed.ac.uk 
> <mailto:d.scott at ed.ac.uk>> wrote:
>
>     How can I get GAMG to take into account the fact that I have more
>     than one degree of freedom per node when it is producing a coarser
>     grid? I am dealing with a problem in structural mechanics and have
>     an unstructued grid. The matrix is read from a file produced by
>     another application. The components of the displacement for a node
>     are grouped together.
>
>
> GAMG uses the block size from the matrix. Did you set that?
>
>   Thanks,
>
>      Matt
>
I did set the block size but I had a strange result from one of my runs 
and I wanted to check that I had done the right thing. I had seen the 
performance improvement that I expected for a 10^6 x 10^6 matrix but not 
for a 10^7 x 10^7 matrix (for which the performance was worse). I have 
subsequently tried a matrix of intermediate size for which I did see a 
performance improvement. I'll try to find out what is happening with the 
largest matrix.

Thanks,

David

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