slepc-3.18.2 2023-01-26
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# NEPSLPSetDeflationThreshold

Sets the threshold value used to switch between deflated and non-deflated iteration.

### Synopsis

    #include "slepcnep.h"
    PetscErrorCode NEPSLPSetDeflationThreshold(NEP nep,PetscReal deftol)

Logically Collective on nep

### Input Parameters

| nep | - nonlinear eigenvalue solver
| deftol | - the threshold value

### Options Database Keys

| -nep_slp_deflation_threshold <deftol> | - set the threshold

### Notes

Normally, the solver iterates on the extended problem in order to deflate previously converged eigenpairs. If this threshold is set to a nonzero value, then once the residual error is below this threshold the solver will continue the iteration without deflation. The intention is to be able to improve the current eigenpair further, despite having previous eigenpairs with somewhat bad precision.

### See Also

NEPSLPGetDeflationThreshold()

### Level

advanced

### Location

src/nep/impls/slp/slp.c
Index of all NEP routines
Table of Contents for all manual pages
Index of all manual pages