[petsc-users] minres: PETSc&MATLAB

Barry Smith bsmith at mcs.anl.gov
Wed Apr 7 18:49:02 CDT 2010


    Send one of the matrices with this behavior to petsc-maint at mcs.anl.gov 
  and we'll see what is going on. Also in that email tell use exactly  
how you run it in Matlab.


On Apr 7, 2010, at 5:58 PM, Umut Tabak wrote:

> Dear all,
> I have tried on some ill-conditioned(indefinite actually) matrices  
> some iterative solutions first with minres of Matlab. Matlab  
> converged in something like 30 iterations to some reasonable  
> tolerances, say 1e-5, without any preconditioner. However, the same  
> matrices did not converge with the minres solver of PETSc. I  
> wondered what could be the differences in implementation? I would  
> expect PETSc to perform better, no supporting arguments for this  
> expectation though.
> I read the matrices in binary format, and use on the command  
> line(with some modifications on the ex1.c code)
> ./ex1 -ksp_type minres -pc_type none
> Best regards,
> Umut

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