solving a particular linear equation system

[Barry Smith]

    Could you please save this matrix and right hand side using - 
ksp_view_binary (just run solver like you usually do but use this  
command line option also) then post the file binaryoutput that is  
generated. This way people can trivially load the matrix and right  
hand side with MatLoad() and not monkey with parsing ASCII files.

   Thanks

    Barry

On May 15, 2009, at 2:29 PM, Christian May wrote:

> Hi everybody,
>
> I have trouble solving a linear equation system with PETSc 3.0.0.
> I tried the following combinations of solvers and preconditioners  
> and list the results:
>
> cg+sor:       Linear solve did not converge due to DIVERGED_NAN
> cg+bjacobi:   Linear solve did not converge due to  
> DIVERGED_INDEFINITE_PC
> cg+ilu:       Linear solve did not converge due to  
> DIVERGED_INDEFINITE_MAT
> gmres+sor:    Linear solve did not converge due to DIVERGED_NAN
> gmres+bjacobi:Linear solve did not converge due to DIVERGED_ITS
> gmres+ilu:    Linear solve did not converge due to DIVERGED_ITS
>
>
> It might be that the matrix is not positive definite, which explains  
> some of the problems. In the last two cases it kind of works, but  
> convergence is horribly slow and it aborts after 10000 iterations.
>
> If somebody could please have a look at the matrix and the right  
> hand side vector, I've put them here:
> http://www.mayarea.de/download/small_matrix.tgz
> The archive contains a file named A.txt, consisting of three columns
> i j Aij and a file b.txt with two columns i and bi.
>
> Any hint on how to solve this linear equation system (in reasonable  
> time) is appreciated.
>
> Thanks a lot in advance!
>
> Christian
>