slepc-main 2024-12-17

SVDSetInitialSpaces

Specify two basis of vectors that constitute the initial right and/or left spaces.

Synopsis

#include "slepcsvd.h" 
PetscErrorCode SVDSetInitialSpaces(SVD svd,PetscInt nr,Vec isr[],PetscInt nl,Vec isl[])

Collective

Input Parameters

	svd	- the singular value solver context
	nr	- number of right vectors
	isr	- set of basis vectors of the right initial space
	nl	- number of left vectors
	isl	- set of basis vectors of the left initial space

Notes

The initial right and left spaces are rough approximations to the right and/or left singular subspaces from which the solver starts to iterate. It is not necessary to provide both sets of vectors.

Some solvers start to iterate on a single vector (initial vector). In that case, the other vectors are ignored.

These vectors do not persist from one SVDSolve() call to the other, so the initial space should be set every time.

The vectors do not need to be mutually orthonormal, since they are explicitly orthonormalized internally.

Common usage of this function is when the user can provide a rough approximation of the wanted singular space. Then, convergence may be faster.

Level

intermediate

Location