EPSSetInitialSpace#

Specify a basis of vectors that constitute the initial space, that is, the subspace from which the solver starts to iterate.

Synopsis#

#include "slepceps.h" 
PetscErrorCode EPSSetInitialSpace(EPS eps,PetscInt n,Vec is[])

Collective

Input Parameters#

  • eps - the linear eigensolver context

  • n - number of vectors

  • is - set of basis vectors of the initial space

Notes#

Some solvers such as EPSKRYLOVSCHUR start to iterate on a single vector (initial vector). In that case, only is[0] is taken into account and the other vectors are ignored. But other solvers such as EPSSUBSPACE are able to make use of the whole initial subspace as an initial guess.

These vectors do not persist from one EPSSolve() 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 eigenspace. Then, convergence may be faster.

See Also#

EPS: Eigenvalue Problem Solver, EPSSetLeftInitialSpace(), EPSSetDeflationSpace()

Level#

intermediate

Location#

src/eps/interface/epssetup.c

Examples#

src/eps/tutorials/ex34.c
src/eps/tutorials/ex19.c
src/eps/tutorials/ex41.c
src/eps/tutorials/ex7.c
src/eps/tutorials/ex5.c

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