[petsc-users] GAMG issue

[Mark F. Adams]

On Mar 14, 2012, at 11:08 AM, John Mousel wrote:

> I'm getting the following error when using GAMG.
> 
> petsc-dev/src/ksp/pc/impls/gamg/agg.c:508: smoothAggs: Assertion `sgid==-1' failed.

Is it possible that your matrix is structurally asymmetric?

This code is evolving fast and so you will need to move to the dev version if you are not already using it. (I think I fixed a bug that hit this assert).

> 
> When I try to alter the type of aggregation at the command line using -pc_gamg_type pa, I'm getting 
> 
> [0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message ------------------------------------
> [1]PETSC ERROR: Unknown type. Check for miss-spelling or missing external package needed for type:
> see http://www.mcs.anl.gov/petsc/documentation/installation.html#external!
> [1]PETSC ERROR: Unknown GAMG type pa given!
> 
> Has there been a change in the aggregation options? I just pulled petsc-dev this morning.
> 

Yes, this option is gone now.  You can use -pc_gamg_type agg for now.

Mark

> John

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