[petsc-users] Mat/Vec with empty ranks

[Florian Lindner]

Hello,

I have a matrix and vector that live on 4 ranks, but only rank 2 and 3 have values:

e.g.

Vec Object: 4 MPI processes
  type: mpi
Process [0]
Process [1]
1.1
2.5
3.
4.
Process [2]
5.
6.
7.
8.
Process [3]


Doing a simple LSQR solve does not converge. However, when the values are distributed equally, it converges within 3
iterations.

What can I do about that?

I have attached a simple program and creates the matrix and vector or loads them from a file.

Thanks,
Florian
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