The options -eps_largest_real -eps_smallest_real are exclusive. The second one, overrides the first one, because both of them call http://slepc.upv.es/documentation/current/docs/manualpages/EPS/EPSSetWhichEigenpairs.html
You should run the example twice, or create a program that calls EPSSolve() twice. Jose > El 27 may 2019, a las 11:36, Afrah Najib via petsc-users > <[email protected]> escribió: > > Hi, > > I have very large matrices and limited CPU hours and I want to get the first > n largest and m smallest eigenvalues form these matrices using SLEPc without > calculating all of them. > > I tried with this command : > > mpirun -n 2 ./ex4 -file bcsstk17.bin -eps_max_it 10000 -eps_ncv 24 -eps_tol > 1.0e-8 -eps_type gd -eps_nev 6 -eps_largest_real -eps_smallest_real > > but it returns the first smallest eigenvalues only. > > Any idea,
