BVMultColumn#

Computes \(y = \beta y + \alpha X q\), where \(y\) is the j-th column of \(X\).

Synopsis#

#include "slepcbv.h" 
PetscErrorCode BVMultColumn(BV X,PetscScalar alpha,PetscScalar beta,PetscInt j,PetscScalar q[])

Logically Collective

Input Parameters#

  • X - a basis vectors object

  • alpha - first scalar

  • beta - second scalar

  • j - the column index

  • q - an array of scalars

Notes#

This operation is equivalent to BVMultVec() but it uses column j of X rather than taking a Vec as an argument. The number of active columns of X is set to j before the computation, and restored afterwards. If X has leading columns specified, then these columns do not participate in the computation. Therefore, the length of array q must be equal to j minus the number of leading columns.

Developer Note#

If q is NULL, then the coefficients are taken from position nc+l of the internal buffer vector, see BVGetBufferVec().

See Also#

BV: Basis Vectors, BVMult(), BVMultVec(), BVMultInPlace(), BVSetActiveColumns()

Level#

advanced

Location#

src/sys/classes/bv/interface/bvops.c

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