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# EPSLANCZOS

EPSLANCZOS = “lanczos” - A basic Krylov method for Hermitian problems, with explicit restart.

## Notes

This solver is very basic and is not recommended in general, since it will not be competitive with respect to other solvers.

The implemented method is Lanczos with explicit restart and deflation. Generally, it is much better to use Lanczos with implicit restart (also known as thick-restart Lanczos) as implemented in `EPSKRYLOVSCHUR`.

Several reorthogonalization strategies can be selected with `EPSLanczosSetReorthog()`. Some of them may result in a cheaper computation, but it will seldom be enough to beat `EPSKRYLOVSCHUR`.

## See Also

EPS: Eigenvalue Problem Solver, `EPS`, `EPSType`, `EPSSetType()`, `EPSLanczosSetReorthog()`

## Level

beginner

## Location

src/eps/impls/krylov/lanczos/lanczos.c

Index of all EPS routines Table of Contents for all manual pages Index of all manual pages