[petsc-users] KrylovSchur solver diverges when setting EPS_GHEP

[Jose E. Roman]

El 07/11/2014, a las 17:31, Denis Davydov escribió:

> 
>> Yes, EPSComputeResidualNorm uses the 2-norm.
> 
> One last thing, if I force EPSSetTrueResidual(eps, PETSC_TRUE)
> will that guarantee that  EPSComputeRelativeError() 
> will give the norm consistent to that, used internally by all SLEPc solvers?
> 
> Thanks.
> Regards,
> Denis.

I would not recommend that, since it is not implemented in all solvers.

I tried with your matrices. In your case, it is much better to compute eigenvalues close to the origin with shift-and-invert, rather than computing smallest_real eigenvalues. That is, replace

-eps_smallest_real

with

-eps_target 0 -st_type sinvert

Jose