Suppose I have a matrix in the form

$\begin{bmatrix} a_1 \\ B \\ c_1 \end{bmatrix} $

(The blocks of this matrix should be vertically stacked...don't know why the latex is wrong)

and its SVD is X. Is there an efficient way of computing the SVD of

$ \begin{bmatrix} a_2 \\ B \\ c_2 \end{bmatrix} $

Where I replace the first row vector and the last row vector with new values, but keep B?

`backwards apostrophes`

or whatever they're called. I also changed "array" to "bmatrix" and took away the delimiters because "bmatrix" provides those. – Michael Hardy Aug 8 '11 at 3:15