How can I use BICGStab on a matrix with zero entries on the diagonal

[Zhu Liang]

By the way, the block of my matrix is like :

U ,     a
A^T ,   0



---------- Forwarded message ----------
From: Zhu Liang <liangcanada at gmail.com>
Date: Aug 13, 2007 5:46 AM
Subject: How can I use BICGStab on a matrix with zero entries on the
diagonal
To: petsc-users at mcs.anl.gov


Dear petsc-users

When I try to solve a linear equation Ax=b with BicgStab preconditioner, I
got
an error "Matrix is missing diagonal number".  That is because I have zeros
on
the diagonal of the matrix.

I am wondering if there is some simple method to avoid that?

Best,
Liang
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