# EPSGetStartVectorLeft

Gets a suitable vector to be used as the starting vector in the recurrence that builds the left subspace (in methods that work with two subspaces).

### Synopsis

    #include "slepceps.h"
    PetscErrorCode EPSGetStartVectorLeft(EPS eps,PetscInt i,Vec vec,PetscBool *breakdown)

Collective on EPS and Vec

### Input Parameters

| eps | - the eigensolver context
| i | - iteration number

### Output Parameter

| vec | - the start vector
| breakdown | - flag indicating that a breakdown has occurred

### Notes

The start vector is computed from another vector: for the first step (i=0), the first left initial vector is used (see EPSSetInitialSpaceLeft()); otherwise a random vector is created. Then this vector is forced to be in the range of OP' and orthonormalized with respect to all W-vectors up to i-1.

The flag breakdown is set to true if i>0 and the vector is linearly dependent with respect to the W-vectors.

The caller must pass a vector already allocated with dimensions conforming to the left initial vector. This vector is overwritten.

### See Also

EPSSetInitialSpaceLeft()

Location: src/eps/interface/solve.c
Index of all EPS routines
Table of Contents for all manual pages
Index of all manual pages