sub_pc lu zero pivot

Matthew Knepley knepley at
Fri Feb 8 12:02:45 CST 2008

We would like to see:

  1) The complete error message

  2) The output of -snes_view so we can see exactly what solver setup you have



On Feb 8, 2008 11:46 AM, Andrew T Barker <Andrew.Barker at> wrote:
> For my code on a single processor, using the options
> -ksp_type gmres -pc_type lu
> works fine, but
> -ksp_type gmres -pc_type asm -sub_pc_type lu
> produces a zero pivot.  On one processor I would expect these two to be identical, and in fact when I print out the asm submatrices (there is only one) in the second case and the original matrix in the first case, they are identical.  Even stranger is that
> -ksp_type gmres -pc_type lu -sub_pc_type lu
> also produces a zero pivot.  I would expect it to ignore the sub_pc in this case.
> Thanks for any help,
> Andrew
> ---
> Andrew T. Barker
> andrew.barker at
> Applied Math Department
> University of Colorado, Boulder
> 526 UCB, Boulder, CO 80309-0526

What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which
their experiments lead.
-- Norbert Wiener

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