slepc-3.18.2 2023-01-26
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# BVTensorBuildFirstColumn

Builds the first column of the tensor basis vectors V from the data contained in the first k columns of U.

### Synopsis

    #include "slepcbv.h"
    PetscErrorCode BVTensorBuildFirstColumn(BV V,PetscInt k)

Collective on V

### Input Parameters

| V | - the basis vectors context
| k | - the number of columns of U with relevant information

### Notes

At most d columns are considered, where d is the degree of the tensor BV. Given V = (I otimes U) S, this function computes the first column of V, that is, it computes the coefficients of the first column of S by orthogonalizing the first d columns of U. If k is less than d (or linearly dependent columns are found) then additional random columns are used.

The computed column has unit norm.

### See Also

BVCreateTensor()

### Level

advanced

### Location

src/sys/classes/bv/impls/tensor/bvtensor.c
Index of all BV routines
Table of Contents for all manual pages
Index of all manual pages