当P=1/2时 P()=1LG(+)+G(-f)] x16(G(O)[(f+f)+(f-)6 当P=1/2时 pE ( f ) = [ ( ) ( ) ] 16 1 2 2 s c c f G f + f + G f − f (0) [ ( ) ( )] 16 1 2 2 s c c + f G  f + f + f − f