[petsc-users] [mumps-users] MUMPS error

[Mrinal Iyer]

Hi,

It seems to me that you have misunderstood the usage of Petsc's
MatXSetPreallocation. With a 27 point stencil, the "total" number of
non-zeros in a row must be 27. You need to split this up into those
interactions that are local and those that are off-proc.  Setting off-proc
nnz to be 27 is way too high. You are running out of memory.

Mrinal


On Sat, Feb 23, 2013 at 4:09 AM, Hui Zhang <mike.hui.zhang at hotmail.com>wrote:

> No, it is a 27-stencil discretization.  I use petsc MatXSetPreallocation
> with much larger estimates for off-diagonal (i.e. on other processors)
> zeros.  Basically, I say 27 non-zeros per row are on other processors.
>  Does this cause the MUMPS error?  Thanks a lot!
>
> On Feb 23, 2013, at 9:56 AM, paresh murthy wrote:
>
> > Hello Mike,
> >
> > I would guess, as perhaps others might as well, that it is trying to
> solve a million x million dense matrix.
> > Are you sure you have removed the zeroes and given it a sparse matrix ?
> >
> > Paresh
> >
> >
> > From: Hui Zhang <mike.hui.zhang at hotmail.com>
> > To: mumps-users at listes.ens-lyon.fr; PETSc users list <
> petsc-users at mcs.anl.gov>
> > Cc: Hui Zhang <mike.hui.zhang at hotmail.com>
> > Sent: Saturday, February 23, 2013 9:51 AM
> > Subject: [mumps-users] MUMPS error
> >
> > Error reported by MUMPS in numerical factorization phase: Cannot
> allocate required memory 70397575 megabytes
> >
> > The required memory is too large. Is that normal? I'm solving a
> Helmholtz equation on 100^3 mesh partitioned to 4^3 processors.
> >
> >
> >
> >
>
>
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