[petsc-users] Setting up MUMPS in PETSc

[Alexander Grayver]

Jinquan,

As a rule of thumb, you should always try to run MUMPS on as few nodes 
as possible which have as much memory as possible. Given the same 
matrix, MUMPS requires more memory when run with, for instance, 4 
process than with 2. You gain nothing trying thousands of processes 
without even looking at statistics mumps gives you (through its output).

If your matrix is symmetric you should use cholesky (LDL^T) 
factorization in MUMPS. This will save a lot of memory and time.

To estimate conditioning of the problem you may also consider the 
algorithm described here:
http://scicomp.stackexchange.com/questions/3486/what-are-the-symptoms-of-ill-conditioning-when-using-direct-methods

It is easy to implement it using MUMPS.

-- 
Regards,
Alexander