[petsc-dev] Symmetry acceleration of the Jacobi-Davidson method (in SLEPc)

[Jose E. Roman]

El 13/02/2015, a las 15:06, Krzysztof Gawarecki escribió:

> Dear All,
> 
> I'm calculating eigenvalues and eigenvectors of the matrix which has specific kind of symmetry.
> Due to this symmetry I obtain the eigenvalues which are doubly degenerated. 
> So eg. eigeinvalue 'e1' has eigenvectors 'a1' and 'b1'. These eigenvectors are related to each other by the relation a1 = T b1, where T is a matrix (given for my problem).
> So it is enough to calculate only one eigenvector for each eigenvalue (and the second one can be calculated by matvec operation). This situation has been described in http://dl.acm.org/citation.cfm?id=2494747.
> 
> How could I take advantage on this in EPSSolve in Jacobi-Davidson method? 
> Could I add two vectors to the subspace (the second one would be calculated by multiplying the first one by matrix T) in every iteration? Should I modify function "dvd_updateV_update_gen" in dvd_updatev.c ? 
> 
> I would be very grateful for any suggestion.
> 
> Krzysztof
> 

We do not provide a flexible way for user-provided subspace expansions, so yes you can try this route by modifying that function yourself. Sent an email to slepc-maint if you get stuck.

Jose