BVMultColumn#
Computes y = betay + alphaX*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 Notes#
If q is NULL, then the coefficients are taken from position nc+l of the internal buffer vector, see BVGetBufferVec().
See Also#
BVMult()
, BVMultVec()
, BVMultInPlace()
, BVSetActiveColumns()
Level#
advanced
Location#
src/sys/classes/bv/interface/bvops.c
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