h2=NhN-N-∑∑n(Mj)hn(Mj)+∑∑n(Mj) =∑∑，(Mj)nN-∑∑(Mj)h,(M) =-∑∑，(M,h4M2 N =-2Σ2 =-N∑fhf 所以 S=-kB∑fhfi       = − = − = − = −  = − − + i i i j i j i j i j i j i j i j i j i j i j N f f N n M N n M N N n M n M n M N n M n M N N N n M n M n M ln ( ) ln ( ) ( ) ( )ln ( )ln ( )ln ( ) ln ln ( )ln ( ) ( ) 所以 = − B  i i S k N f ln f