[petsc-users] incomplete cholesky with a drop tolerance

Umut Tabak u.tabak at tudelft.nl
Sun Jul 22 09:49:26 CDT 2012

Dear all,

I am testing some iterative methods with MATLAB and aside with PETSc 
however I have a question which might be answered in the documentation 
however I could not find that?

In MATLAB, at least on recent versions, one can specify a drop tolerance 
for the incomplete cholesky preconditioner, I was wondering if the same 
is possible with PETSc or not?

One more question, is the condition number order 1e+6(estimated with 
condest in MATLAB) rather high for an iterative method? With icc, with a 
drop tolerance of 1e-3 or 1e-4, as a preconditioner to pcg, I can get 
decent iteration numbers to convergence in MATLAB, it is sometimes even 
faster than solving the system with the available factorization 
information and I was wondering if I can make it faster with some other 
options in PETSc or not?

Best regards,

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