Function Reference
— Loadable Function: [Q1, R1] = qrinsert (Q, R, j, x, orient)

Given a QR factorization of a real or complex matrix A = Q*R, Q unitary and R upper trapezoidal, return the QR factorization of [A(:,1:j-1) x A(:,j:n)], where u is a column vector to be inserted into A (if orient is "col"), or the QR factorization of [A(1:j-1,:);x;A(:,j:n)], where x is a row vector to be inserted into A (if orient is "row").

The default value of orient is "col".

If orient is "col" and the matrix Q is not square, then what gets inserted is the projection of u onto the space spanned by columns of Q, i.e. Q*Q'*u.

If orient is "row", Q must be square.

See also: qr qrupdate qrdelete