[petsc-users] Zero diagonal term for direct solver

[Qin Lu]

Hello,
I am using the Petsc native direct solver (with KSPPREONLY and PCLU) to solver a small Linear equation system. The matrix has a couple of diagonal terms with value 0, which makes the solver fail. Then I set a very small value (e.g., 1e-10) at these terms and the solver works. Can this cause noticeable errors in the solution? Are there any options in Petsc to make the direct solver do row/column pivoting so that all the diagonal terms are non-zero?
Thanks for any suggestions.
Regards,Qin
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