slepc-3.17.0 2022-03-31
Report Typos and Errors

# 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 on eps

### Input Parameters

| eps | - the eigenproblem solver context
| n | - number of vectors
| is | - set of basis vectors of the initial space

### Notes

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 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

EPSSetLeftInitialSpace(), EPSSetDeflationSpace()

Location: src/eps/interface/epssetup.c

### Examples

src/eps/tutorials/ex5.c.html
src/eps/tutorials/ex7.c.html
src/eps/tutorials/ex19.c.html
src/eps/tutorials/ex34.c.html
src/eps/tutorials/ex41.c.html
Index of all EPS routines
Table of Contents for all manual pages
Index of all manual pages