[Q,R] = qrinsert(Q,R,j,x)
[Q,R] = qrinsert(Q,R,j,x), where the inputs Q and R are the original QR factorization of a matrix A, returns Q and R as the QR factorization of the matrix A with an additional column, x, inserted before A(:,j). If A has n columns and j = n+1, then qrinsert inserts x after the last column of A.
qrinsert inserts the values of x into the j-th 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 j-th column.
qr,qrdelete
(c) Copyright 1994 by The MathWorks, Inc.