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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