[petsc-users] [petsc-dev] Two questions about PC Object

[Jakub Sistek]

Hello,

let me add that MUMPS has a nice manual that describes well the error 
codes in Section 7.
( http://graal.ens-lyon.fr/MUMPS/doc/userguide_4.10.0.pdf ).
> Error reported by MUMPS in numerical factorization phase: INFO(1)=-1, INFO(2)=359

> 1) Does anybody know what the error INFO(1)=-1 means in MUMPS?
Regarding INFO(1) = -1 the manual says:
"An error occurred on processor INFO(2)"
I think that it works the way that all processes has the same INFO(1) 
and INFO(2) except proc 359, which in fact contain the 'real' error in 
its INFO(1).

According to my experience with MUMPS, if you solve on large number of 
processors, you might get a bit underestimated sizes of work arrays to 
allocate. One then needs to relax the estimate by ICNTL(14) parameter 
which tells in percent how much memory to add to the estimate. This is 
achieved through PETSc e.g. by command line option -mat_mumps_icntl_14:
|-ksp_type preonly -pc_type lu -pc_factor_mat_solver_package mumps 
-mat_mumps_icntl_14 50|
which tells MUMPS to add 50% to the estimate.
This might be worth trying, it resolves most of similar problems to me, 
but I do not know if this is the source of your problems as well. I am 
not sure if one can get to INFO(1) value on process 359 through PETSc.

Best regards,

Jakub

-- 
Jakub Sistek, Ph.D.
postdoctoral researcher
Institute of Mathematics of the AS CR
http://www.math.cas.cz/~sistek/
tel: (+420) 222 090 710

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