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

[Jose E. Roman]

El 12/04/2013, a las 15:22, Zhang Wei escribió:

> Dear Sir:
> I am using slepc for hydrodynamic instability analysis. From my understanding most of these unstable modes in hydrodynamic are large scale structure with low frequency, which means very small angle for the complex eigenvalue. Actually I tried a channel flow case, finally I got several Eigen value with imaginary part is exact 0. and from the Eigen modes,  it gives "correct" results in one direction but not wave, since the wave number is 0. So I suppose there must be algorithm to control so. Does any one know what could influence so?
> 
> 
> Best Regards
> 
> Wei  	   		  

I don't understand what your problem is. Can you express it in terms of the algebraic eigenproblem? Are you getting wrong solutions for the eigenproblem? Did you check the residual of the eigenpairs?

Jose