Thank you very much. Regards,
---------------------------------------- > Subject: Re: [petsc-users] Slepc doesn't converge for some EV problems > From: [email protected] > Date: Wed, 5 Jun 2013 08:33:31 +0200 > CC: [email protected] > To: [email protected] > > > El 05/06/2013, a las 07:52, Sonya Blade escribió: > >> Dear All, >> >> Sometimes I experience that Slepc is not converging for the requested >> eigenvalues and simply resturns 0. I do take into consideration of setting >> the requested eigenvalues from command line options rather then setting them >> manually at the body of program. >> >> I observe this when I'm trying to solve this moderately large matrices e.g. >> 192x192 >> for small ones e.g. 48x48 there is not problem other than Slepc deviates from >> requested to found EVs. For example if I request 7 eigenvalues to be found >> Slepc finds >> 9 or 10, what could be the problem of this malfunctioning? >> >> Your help will be appreciated, >> >> Regards, > > 192 is very small. SLEPc is intended for large sizes (10,000 or more). For > such small matrices, you would rather use LAPACK. > > It is normal that the solver returns more eigenvalues than requested. This is > not a malfunctioning. > > If you get zero converged eigenvalues, try changing the parameters (e.g. ncv) > or using a different strategy (e.g. shift-and-invert with a reasonable > target). > > Jose >
