slepc-3.13.0 2020-03-31
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SVDSetDimensions

Sets the number of singular values to compute and the dimension of the subspace.

Synopsis

#include "slepcsvd.h" 
PetscErrorCode SVDSetDimensions(SVD svd,PetscInt nsv,PetscInt ncv,PetscInt mpd)
Logically Collective on svd

Input Parameters

svd  - the singular value solver context
nsv  - number of singular values to compute
ncv  - the maximum dimension of the subspace to be used by the solver
mpd  - the maximum dimension allowed for the projected problem

Options Database Keys

-svd_nsv <nsv>  - Sets the number of singular values
-svd_ncv <ncv>  - Sets the dimension of the subspace
-svd_mpd <mpd>  - Sets the maximum projected dimension

Notes

Use PETSC_DEFAULT for ncv and mpd to assign a reasonably good value, which is dependent on the solution method and the number of singular values required.

The parameters ncv and mpd are intimately related, so that the user is advised to set one of them at most. Normal usage is that (a) in cases where nsv is small, the user sets ncv (a reasonable default is 2*nsv); and (b) in cases where nsv is large, the user sets mpd.

The value of ncv should always be between nsv and (nsv+mpd), typically ncv=nsv+mpd. If nsv is not too large, mpd=nsv is a reasonable choice, otherwise a smaller value should be used.

See Also

SVDGetDimensions()

Location: src/svd/interface/svdopts.c
Index of all SVD routines
Table of Contents for all manual pages
Index of all manual pages

Examples

src/svd/tutorials/ex8.c.html