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qrinsert | See Also |
Insert column in QR factorization
[Q,R] = qrinsert(Q,R,j,x)
[Q,R] = qrinsert(Q,R,j,x)
changes Q
and R
to be the factorization of the matrix obtained by inserting an extra column, x
, before A(:,j)
. If A
has n
columns and j
=
n+1
, then qrinsert
inserts x
after the last column of A
.
Inputs Q
and R
represent the original QR factorization of matrix A
, as returned by the statement [Q,R] = qr(A)
. Argument x
is the column vector to be inserted into matrix A
. Argument j
specifies the column before which x
is inserted.
The qrinsert
function inserts the values of x
into the jth column of R
. It then uses a series of Givens rotations to zero out the nonzero elements of R
on and below the diagonal in the jth column.
qr
Orthogonal-triangular decomposition
qrdelete
Delete column from QR factorization