[Trilinos-Users] [EXTERNAL] small question concerning ML
Tuminaro, Raymond S
rstumin at sandia.gov
Thu Mar 21 08:58:27 MDT 2013
Riccardo,
It looks like the ILU smoother is never "really" set. I'm not sure why this would be because it looks
you've set up the parameter list correctly. Is there any chance that IFPACK is not configured in
your build? You should have somewhere a libifpack.a in your compiled Trilinos?
-Ray
________________________________
From: trilinos-users-bounces at software.sandia.gov [trilinos-users-bounces at software.sandia.gov] on behalf of Riccardo Rossi [rrossi at cimne.upc.edu]
Sent: Thursday, March 21, 2013 2:40 AM
To: trilinos-users at software.sandia.gov
Subject: [EXTERNAL] [Trilinos-Users] small question concerning ML
Dear list,
i am trying to use ILU0 smoother together with ML to see if it can improve convergence, with a problem which corresponds to a pde size of 4
the thing is that if i use the following
ML_Epetra::SetDefaults("NSSA", MLList, options, params);
MLList.set("PDE equations", mNumDof);
MLList.set("null space: add default vectors", true);
MLList.set("aggregation: type","Uncoupled");
it works correctly
but if i put the following settings
MLList.set("PDE equations", mNumDof);
MLList.set("null space: add default vectors", true);
MLList.set("aggregation: type","Uncoupled"); <----- up to this point exactly identical
MLList.set("smoother: type","IFPACK");
MLList.set("smoother: ifpack type", "ILU");
MLList.set("smoother: ifpack overlap", 0);
MLList.sublist("smoother: ifpack list").set("fact: level-of-fill", 0);
MLList.set("ML output",5);
MLList.set("print unused",1);
than it does not even try to iterate and gives the output posted at the end of the email (provding at the end a wrong result):
can anyone give a hint of what can i be doing wrong? changing overlap and level of fill does not improve the situation
also commenting the line
MLList.set("null space: add default vectors", true);
does not help
any suggestion is welcome
thank you in advance
Riccardo
System Solve Time : 5.44
Building Time : 2.86
ML_Aggregate_Coarsen (level 0) begins
ML_Aggregate_CoarsenUncoupled : current level = 0
ML_Aggregate_CoarsenUncoupled : current eps = 0.000000e+00
Aggregation(UVB) : Total nonzeros = 25542464 (Nrows=438016)
Aggregation(UVB) : Amalgamated matrix done
Aggregation(UC) : Phase 0 - no. of bdry pts = 0
Aggregation(UC) : Phase 1 - nodes aggregated = 71810 (109504)
Aggregation(UC) : Phase 1 - total aggregates = 5698
Aggregation(UC_Phase2_3) : Phase 1 - nodes aggregated = 71027
Aggregation(UC_Phase2_3) : Phase 1 - total aggregates = 5698
Aggregation(UC_Phase2_3) : Phase 2a- additional aggregates = 237
Aggregation(UC_Phase2_3) : Phase 2 - total aggregates = 5935
Aggregation(UC_Phase2_3) : Phase 2 - boundary nodes = 1226
Aggregation(UC_Phase2_3) : Phase 3 - leftovers = 0 and singletons = 0
ML_Aggregate_Coarsen (level 1) begins
ML_Aggregate_CoarsenUncoupled : current level = 1
ML_Aggregate_CoarsenUncoupled : current eps = 0.000000e+00
Aggregation(UVB) : Total nonzeros = 4840413 (Nrows=23740)
Aggregation(UVB) : Amalgamated matrix done
Aggregation(UC) : Phase 0 - no. of bdry pts = 0
Aggregation(UC) : Phase 1 - nodes aggregated = 3526 (5935)
Aggregation(UC) : Phase 1 - total aggregates = 97
Aggregation(UC_Phase2_3) : Phase 1 - nodes aggregated = 3526
Aggregation(UC_Phase2_3) : Phase 1 - total aggregates = 97
Aggregation(UC_Phase2_3) : Phase 2a- additional aggregates = 25
Aggregation(UC_Phase2_3) : Phase 2 - total aggregates = 122
Aggregation(UC_Phase2_3) : Phase 2 - boundary nodes = 2
Aggregation(UC_Phase2_3) : Phase 3 - leftovers = 0 and singletons = 0
ML_Aggregate_Coarsen (level 2) begins
ML_Aggregate_CoarsenUncoupled : current level = 2
ML_Aggregate_CoarsenUncoupled : current eps = 0.000000e+00
Aggregation(UVB) : Total nonzeros = 97790 (Nrows=488)
Aggregation(UVB) : Amalgamated matrix done
Aggregation(UC) : Phase 0 - no. of bdry pts = 0
Aggregation(UC) : Phase 1 - nodes aggregated = 94 (122)
Aggregation(UC) : Phase 1 - total aggregates = 5
Aggregation(UC_Phase2_3) : Phase 1 - nodes aggregated = 94
Aggregation(UC_Phase2_3) : Phase 1 - total aggregates = 5
Aggregation(UC_Phase2_3) : Phase 2a- additional aggregates = 1
Aggregation(UC_Phase2_3) : Phase 2 - total aggregates = 6
Aggregation(UC_Phase2_3) : Phase 2 - boundary nodes = 0
Aggregation(UC_Phase2_3) : Phase 3 - leftovers = 0 and singletons = 0
Smoothed Aggregation : operator complexity = 1.193356e+00.
Amesos (level 3) : NumGlobalRows = 24
Amesos (level 3) : NumGlobalNonzeros = 576
Amesos (level 3) : Fill-in = 100 %
Amesos (level 3) : Building KLU
Amesos (level 3) : Time for factorization = 0.000393867 (s)
*******************************************************
***** Problem: Epetra::CrsMatrix
***** Preconditioned GMRES (with condnum) solution
***** ML (L=4, ~/IFPACK_post0, ~/Amesos_KLU_3)
***** No scaling
*******************************************************
iter: 0 residual = 1.000000e+00
***************************************************************
Warning: the GMRES Hessenberg matrix is ill-conditioned. This may
indicate that the application matrix is singular. In this case, GMRES
may have a least-squares solution.
Solver: gmres_condnum
number of iterations: 1
Actual residual = 3.0313e+00 Recursive residual = 3.0313e+00
Calculated Norms Requested Norm
-------------------------------------------- --------------
||r||_2 / ||r0||_2: 1.000000e+00 1.000000e-08
-----------------------------------------------------
Warning : The Hessenberg matrix is too small
Analysis of the Hessenberg matrix:
smallest eigenvalue (in module) = 1.000000e+00
largest eigenvalue (in module) = 1.000000e+00
***************************************************************
estimated condition number = 1.000000e+00
-----------------------------------------------------
Solution time: 0.594218 (sec.)
total iterations: 1
Linear solver
--
Dr. Riccardo Rossi, Civil Engineer
Member of Kratos Team
International Center for Numerical Methods in Engineering - CIMNE
Campus Norte, Edificio C1
c/ Gran Capitán s/n
08034 Barcelona, España
Tel: (+34) 93 401 56 96
Fax: (+34) 93.401.6517
web: www.cimne.com<http://www.cimne.com/>
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