说明：  增量奇异值分解算法，来至MIT大学的wingate教授，含3个源码.
(Given the thin SVD of a matrix (X=USV ), update it in a number of interesting ways, while preserving the rank of the result. svd_update.m- update the SVD to be [X+ A *B]=Up*Sp*Vp (a general matrix update). addblock_svd_update.m- update the SVD to be [X A] = Up*Sp*Vp (add columns [ie, new data points]) rank_one_svd_update.m- update the SVD to be [X+ a*b ] = Up*Sp*Vp (that is, a general rank-one update. This can be used to add columns, zero columns, change columns, recenter the matrix, etc. ).)