This type of method requires a very high degree polynomial; suggest using degree=100 at least (this is the default value), but larger values may be necessary. Also, for this particular filter the "range" must be approximately equal to the numerical range; if you have no clue where your first and last eigenvalues are, you may use EPSSolve() calls with EPS_LARGEST_REAL and EPS_SMALLEST_REAL.
Jose > El 10 oct 2018, a las 21:10, Moritz Cygorek <mcygo...@uottawa.ca> escribió: > > Thank you for the fast reply. > > I've tried running my program (using the defaul Krylov-Schur method for > sparse MPI matrices) with the additional options: > > -st_type filter -st_filter_degree 2 -st_filter_interval 2.,2.7 > -st_filter_range -2000,2000 > > and I get the following error message: > > [0]PETSC ERROR: STFILTER cannot get the filter specified; please adjust your > filter parameters (e.g. increasing the polynomial degree) > .... > [0]PETSC ERROR: #1 FILTLAN_GetIntervals() line 451 in > /home/applications/sources/libraries/slepc-3.9.2/src/sys/classes/st/impls/filter/filtlan.c > [0]PETSC ERROR: #2 STFilter_FILTLAN_setFilter() line 1016 in > /home/applications/sources/libraries/slepc-3.9.2/src/sys/classes/st/impls/filter/filtlan.c > [0]PETSC ERROR: #3 STSetUp_Filter() line 42 in > /home/applications/sources/libraries/slepc-3.9.2/src/sys/classes/st/impls/filter/filter.c > [0]PETSC ERROR: #4 STSetUp() line 271 in > /home/applications/sources/libraries/slepc-3.9.2/src/sys/classes/st/interface/stsolve.c > [0]PETSC ERROR: #5 EPSSetUp() line 263 in > /home/applications/sources/libraries/slepc-3.9.2/src/eps/interface/epssetup.c > [0]PETSC ERROR: #6 EPSSolve() line 135 in > /home/applications/sources/libraries/slepc-3.9.2/src/eps/interface/epssolve.c > > > > Do you have a clue what I've missed? > > > Moritz > > > From: Jose E. Roman <jro...@dsic.upv.es> > Sent: Wednesday, October 10, 2018 2:30 PM > To: Moritz Cygorek > Cc: petsc-users@mcs.anl.gov > Subject: Re: [petsc-users] STFILTER in slepc > > > > El 10 oct 2018, a las 19:54, Moritz Cygorek <mcygo...@uottawa.ca> escribió: > > > > Hi, > > > > in the list of changes to SLEPc version 3.8, it is stated that there is a > > preliminary implementation of polynomial filtering using STFILTER. > > > > Because I am struggling to obtain interior eigenvalues and harmonic > > extraction seems not to be stable enough in my case, I wanted to give it a > > try, but I could not find any documentation yet. > > > > Does anybody have an example of how to use STFILTER or any documentation > > about it? > > > > Thanks in advance, > > Moritz > > There are no examples. You just set the type to STFILTER and set some > parameters such as the interval of interest or the polynomial degree. See > functions starting with STFilter > here:http://slepc.upv.es/documentation/current/docs/manualpages/ST/index.html > > In some problems it works well, but don't expect too much. It is still in our > to-do list to make it more usable. It will be good to have your feedback. If > you want, send results to slepc-maint, maybe we can help tuning the > parameters. > > Jose
