SVDGetSingularTriplet — SLEPc 3.25.0 documentation

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# SVDGetSingularTriplet

Gets the `i`-th triplet of the singular value decomposition as computed by `SVDSolve()`. The solution consists in the singular value and its left and right singular vectors.

## Synopsis

    #include "slepcsvd.h"
    PetscErrorCode SVDGetSingularTriplet(SVD svd,PetscInt i,PetscReal *sigma,Vec u,Vec v)

Collective

## Input Parameters

- svd - the singular value solver context

- i - index of the solution

## Output Parameters

- sigma - singular value

- u - left singular vector

- v - right singular vector

## Note

Both `u` or `v` can be `NULL` if singular vectors are not required. Otherwise, the caller must provide valid `Vec` objects, i.e., they must be created by the calling program with e.g. `MatCreateVecs()`.

The index `i` should be a value between 0 and `nconv`-1 (see `SVDGetConverged()`). Singular triplets are indexed according to the ordering criterion established with `SVDSetWhichSingularTriplets()`.

In the case of GSVD, the solution consists in three vectors \(u\), \(v\), \(x\) that are returned as follows. Vector \(x\) is returned in the right singular vector (argument `v`) and has length equal to the number of columns of \(A\) and \(B\). The other two vectors are returned stacked on top of each other \([u^*,v^*]^*\) in the left singular vector argument `u`, with length equal to \(m+n\) (number of rows of \(A\) plus number of rows of \(B\)).

## See Also

SVD: Singular Value Decomposition, `SVDSolve()`, `SVDGetConverged()`, `SVDSetWhichSingularTriplets()`

## Level

beginner

## Location

src/svd/interface/svdsolve.c

## Examples

src/svd/tutorials/ex53.c
src/svd/tutorials/ex45.c
src/svd/tutorials/ex15.c
src/svd/tutorials/ex15f.F90
src/svd/tutorials/ex8.c
src/svd/tutorials/ex52.c

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