Modifying the singular value decomposition on the connection machine

A fully parallel algorithm for updating and downdating the singular value decompositions (SVD's) of an m-by-n (m greater than or equal to n) matrix A is described. The algorithm uses similar chasing techniques for modifying the SVD's described in [3], but requires fewer plane rotations, and can be implemented almost identically for both updating and downdating. Both cyclic and consecutive storage schemes are considered in parallel implementation. We show that the latter scheme outperforms the former on a distributed memory MIMD multiprocessor. We present the experimental results on the 32-node Connection Machine (CM-5).