function?[SwSb]=calculate2（trainsampletrainlabel）
%use?caideng‘s?method?to?calculate?SwSbSt
%each?row?of?trainsample?is?a?data?point
%each?column?is?a?feature

[nd]=size（trainsample）;
classlabel=unique（trainlabel）;
nclass=length（classlabel）;

totalmean=?mean（trainsample）;
tm