sub_pc lu zero pivot

Andrew T Barker Andrew.Barker at Colorado.EDU
Fri Feb 8 11:46:09 CST 2008

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 T. Barker
andrew.barker at
Applied Math Department
University of Colorado, Boulder
526 UCB, Boulder, CO 80309-0526

More information about the petsc-users mailing list