[Trilinos-Users] AztecOO: not enough memory for ILUT

Tiziano Passerini tiziano.passerini at polimi.it
Wed Feb 27 10:28:59 MST 2008

Good morning,

I downloaded and compiled Trilinos 8.0.5 and now I'm using AztecOO to  
solve a linear system A * x = b coming from finite element spatial  
discretization of Navier-Stokes equations. It's not exactly a big  
system (200k unknowns) but still I have some unexpected troubles.

I'm running AztecOO on a single processor (no MPI support); I use  
gmres solver, with the builtin domain decomposition preconditioner and  
subdomain solver ILUT.

Actually my matrix A is ill conditioned, and I played a little with  
AztecOO solver params to get convergence in a reasonable number of  
iterations. I increased the size of the krylov space, added row  
scaling to the matrix and most of all I increased ILUT fill-in. This  
is the point, since for large values of ILUT fill-in I got

"ERROR: not enough memory for ILUT. Decrease fill-in or increase drop  

However, I'm running my job on a server with 32 GB RAM and 64 bit cpu,  
and my job aborts after filling less than 3 GB RAM.

Is that an expected behaviour?

Thanks in advance for any suggestion.

Tiziano Passerini

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org:Politecnico di Milano;MOX Dipartimento di Matematica
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email;internet:tiziano.passerini at polimi.it
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