[Trilinos-Users] 2D diffusion problem with MPI

Olivia Buzek obuzek at nist.gov
Thu Jun 26 13:31:46 MDT 2008

I am trying to solve a 2D diffusion problem in parallel using MPI and

The relevant pieces of the code I have been using are as follows:

(size is the dimension of the matrix, currently set to 25; bandwidth
is currently set to 3)

    m = Epetra.Map(size, 0, comm)
    r = Epetra.Map(size,size,0,comm)
    A= Epetra.CrsMatrix(Epetra.Copy, m, r, 3*bandwidth/2)
    b = Epetra.Vector(m)
    b.ReplaceGlobalValues(...[initial values]...)
    x = Epetra.Vector(m)

    solver = AztecOO.AztecOO(A, x, b)
    solver.SetAztecOption(AztecOO.AZ_solver, AztecOO.AZ_cg)
    solver.SetAztecOption(AztecOO.AZ_output, AztecOO.AZ_none)
    err = solver.Iterate(5000, 1e-10)

Trilinos is compiled properly for MPICH version: 1.2.7p1.  The problem
is being distributed across 2 processors.  Evidently, the matrix is
being built correctly.  However, upon reaching the first solver
statement (initializing AztecOO), the following error is returned:

AZ_extract_comm_info: Received elements must be stored after
                   all 12 local elements

Can anyone advise as to what is going on here?


Olivia Buzek

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