[Trilinos-Users] AMG Preconditioner Neumann Laplacian 32 vs 64 bit issue

[Martin Stoll]

Hi all,

I am using deal.II and from there call the ML AMG preconditioner. I am
using it to approximate a Neumann Laplacian, which works like a charm on
my 32 bit desktop Ubuntu machine and also on my Mac Book Pro running Snow
Leopard. Now copying this to a linux 64 bit machine I get weird results
meaning
that applying the preconditioner results
32 bit
norm(vin)=0.01
APPLY AMG
norm(vout)=0.15

64 bit
norm(vin)=0.01
APPLY AMG
norm(vout)=1e+11

When instead of the Neumann Laplacian I put a mass matrix into the AMG
routine the blow does not happen.

I am not sure where to go from here so I hope I could get some help here.

Best,
Martin



-- 
Martin Stoll
Postdoctoral Research Fellow

Computational Methods in Systems and Control Theory
Max Planck Institute for Dynamics of Complex Technical Systems
Sandtorstr. 1, D-39106 Magdeburg,Germany
Email: martin.stoll80 at gmail.com <stollm at mpi-magdeburg.mpg.de>
URL: http://www.mpi-magdeburg.mpg.de/mpcsc/stollm/

Tel :+49 391 6110 384
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