[petsc-users] Question about rank of matrix

[user_gong Kim]

Hello,

I have a question about rank of matrix.
At the problem
Au = b,

In my case, sometimes global matrix A is not full rank.
In this case, the global matrix A is more likely to be singular, and if it
becomes singular, the problem cannot be solved even in the case of the
direct solver.
I haven't solved the problem with an iterative solver yet, but I would like
to ask someone who has experienced this kind of problem.

1. If it is not full rank, is there a numerical technique to solve it by
catching rows and columns with empty ranks in advance?

2.If anyone has solved it in a different way than the above numerical
analysis method, please tell me your experience.

Thanks,
Hyung Kim
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