El 03/06/2015, a las 18:04, Xujun Zhao escribió: > One problem is that I don't have the explicit form of matrix D, but only u = > D*v which can be obtained from my PETSc solver. How should I set up my > EPSSolver in this case? Are there examples in SLEPc? Thanks. > > Xujun
http://slepc.upv.es/documentation/current/src/eps/examples/tutorials/ex3.c.html http://slepc.upv.es/documentation/current/src/eps/examples/tutorials/ex6f.F.html > > On Wed, Jun 3, 2015 at 10:59 AM, Jose E. Roman <[email protected]> wrote: > > El 03/06/2015, a las 17:47, Xujun Zhao escribió: > > > Hi Jose, > > > > Thank you for your reply. How about the computational cost compared to one > > EPSSolve() with all eigenvalues? what methods does SLEPc use for each > > solve? Because it may be cheaper for largest eigenvalue if the power method > > is used, but I don't if it is still so for smallest eigenvalue? > > > > Xujun > > > > Don't compute all eigenvalues. > > For the largest eigenvalue, don't use the power iteration. The default solver > (Krylov-Schur) will be very fast for that. For the smallest eigenvalue, > convergence may be slow if eigenvalues are small and poorly separated - it > may be necessary to do shift-and-invert, in which case the cost may blow up. > > Jose > >
