function?[USVbndj]?=?lansvd（varargin）
%LANSVD??Compute?a?few?singular?values?and?singular?vectors.
%???LANSVD?computes?singular?triplets?（uvsigma）?such?that
%???A*u?=?sigma*v?and??A‘*v?=?sigma*u.?Only?a?few?singular?values?
%???and?singular?vectors?are?computed??using?the?Lanczos?
%???bidiagonalization?algorithm?with?partial?reorthogonalization?（BPRO）.?
%
%???S?=?LANSVD（A）?
%???S?=?LANSVD（‘Afun‘‘Atransfun‘MN）??
%
%???The?first?input?argument?is?either?a??matrix?or?a
%???string?containing?the?name?of?an?M-file?which?applies?a?linear
%???operator?to?the?columns?of?a?given?matrix.??In?the?latter?case
%???the?second?input?must?be?the?name?of?an?M-file?which?applies?the
%???transpose?of?the?same?operator?to?the?columns?of?a?given?matrix??
%???and?the?third?and?fourth?a