[petsc-users] 答复: algorithm to get pure real eigen valule for general eigenvalue problem(Non-hermitian type)

[Zhang Wei]

Hi 
sorry for didn't properly describe the problem. and you are right, I am talking about restart. I mean I read the source code for wrapping the arpack in slepc. it seems no difference in the implementation as in this FEM code I mentioned before. but it works different from the output point of view. actully there is a parameter as 'keep' extact the same as in kryloyschur solver in wrapped arpack in slepc, when we use this FEM codes, it only throw out the first vector in krylov space. how can I let the arpack work as that in slepc?   
________________________________________
发件人: petsc-users-bounces at mcs.anl.gov [petsc-users-bounces at mcs.anl.gov] 代表 Jose E. Roman [jroman at dsic.upv.es]
发送时间: 2013年4月16日 8:54
收件人: PETSc users list
主题: Re: [petsc-users] algorithm to      get     pure    real    eigen   valule  for     general eigenvalue      problem(Non-hermitian type)

El 15/04/2013, a las 23:18, Zhang Wei escribió:

> hi
> Thanks very much for your help!
> Indeed, I am dealing with linearised Navier Stokes.  Actually the algorithm is already tested in a FEM code by directly using Arpack. I tried slepc with wrapped Arpack. I noticed that the shit between each iteration is controlled by the number of converged eigenvalue and a predefined portion,which is the same as restart parameter "keep" in krylovschur solver, but can't be changed. While in the FEM code, the shift value is exact one. But I can't find different in the implementation. Could it be the problem?
>
> Yours Sincerely
> ------------------------
> Wei Zhang
> Ph.D
> Hydrodynamic Group
> Dept. of Shipping and Marine Technology
> Chalmers University of Technology
> Sweden
> Phone:+46-31 772 2703

Which shift? Do you mean doing shift-and-invert? This has nothing to do with the restart parameter.

Jose