[petsc-users] Getting n largest and m smallest eigenvalues from SLEPc at the same time

[Afrah Najib]

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,
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