| MATLAB Function Reference | |
Insert column in QR factorization
Syntax
[Q,R] = qrinsert(Q,R,j,x)
Description
[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.
Algorithm
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.
See Also
| | qrdelete | qrupdate | |