[petsc-users] PC Direct Solution failure

[Matthew Overholt]

PETSc Users,

 

I am doing a KSPPREONLY solution (of the heat transfer equation using FEA)
and comparing several packages like PARDISO and MUMPS, and I am encountering
a MatSolve() failure that I am having trouble diagnosing.  The matrix
inversion fails and I get "nan".  The failure only happens for certain input
files, and its not (just) related to problem size.  By making a slight
change to the geometry of the problem I can get it to solve.

 

The SuperLu solver is the only one that will give me any error message:

-ksp_type preonly -pc_type lu -pc_mat_solver_package superlu -info

I get the error message:

[0] MatSolve(): MatFactorError 2

Is that a PCFailedReason of PC_FACTOR_NUMERIC_ZEROPIVOT?

If so, is there a way to perturb the pivot in some way?

 

In another (non-PETSc) code which uses MKL PARDISO I am able to solve the
exact same problem by the same approach without any issues, and that code
gives PARDISO a pivot perturbation flag value.

 

Is there a better way to figure out what is happening?  I have been running
the code in TotalView with extreme memory checks and everything appears to
be ok.

 

Thanks,

Matt Overholt

CapeSym, Inc.

 

 



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