** Insert a column in the QR factorization. **

** If [Q,R] = qr(A) is the original QR factorization of A, **

** then [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 x is inserted after the last column of A.) **

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** See also QR , QRDELETE , PLANEROT . **

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