# EPSSetMatrixNorms

Gives the reference values of the matrix norms and specifies whether these values should be improved adaptively.

### Synopsis

    #include "slepceps.h"
    PetscErrorCode EPSSetMatrixNorms(EPS eps,PetscReal nrma,PetscReal nrmb,PetscBool adaptive)

Logically Collective on EPS

### Input Parameters

| eps | - the eigensolver context
| nrma | - a reference value for the norm of matrix A
| nrmb | - a reference value for the norm of matrix B
| adaptive | - whether matrix norms are improved adaptively

### Options Database Keys

| -eps_norm_a <nrma> | - norm of A
| -eps_norm_b <nrma> | - norm of B
| -eps_norms_adaptive <boolean> | - Sets/resets the boolean flag 'adaptive'

### Notes

If the user sets adaptive=PETSC_FALSE then the solver uses the values of nrma and nrmb for the matrix norms, and these values do not change throughout the iteration.

If the user sets adaptive=PETSC_TRUE then the solver tries to adaptively improve the supplied values, with the numerical information generated during the iteration. This option is not available in all solvers.

If a passed value is PETSC_DEFAULT, the corresponding norm will be set to 1. If a passed value is PETSC_DETERMINE, the corresponding norm will be computed as the NORM_INFINITY with MatNorm().

### See Also

EPSGetMatrixNorms()

Location: src/eps/interface/opts.c
Index of all EPS routines
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Index of all manual pages