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

[Alberto F. Martín-Huertas]

 Hi Martin,

 did you observe the same behaviour with a
 Dirichlet Laplacian ?

 Best regards,
  Alberto.

 On Thu, 1 Dec 2011 12:52:08 +0100, Martin Stoll wrote:
> 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 [1]
> URL: http://www.mpi-magdeburg.mpg.de/mpcsc/stollm/ [2]
>
> Tel :+49 391 6110 384
>
>
>
> Links:
> ------
> [1] mailto:stollm at mpi-magdeburg.mpg.de
> [2] http://www.mpi-magdeburg.mpg.de/mpcsc/stollm/

-- 
 Alberto F. Martín-Huertas
 Centre Internacional de Mètodes Numèrics a l'Enginyeria (CIMNE)
 Parc Mediterrani de la Tecnologia, UPC
 Esteve Terrades 5, Building C3, Office 210,
 08860 Castelldefels (Barcelona, Spain)
 Tel.: (+34) 9341 34223
 e-mail: amartin at cimne.upc.edu

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