第二步: (1)=x()+x1(i+2) x2(i+2)=W2{x(i)-x(i+2)]i=0,1,45 第三步 X()=x2()+x2(i+1) X(+4)=x2()-x2(i+1,=0,2 X()=x2(+3)+x2(+4) X(+4)=x2(+3)-x2(+4),i=1,3第二步： 2 1 1 2 2 1 1 ( ) ( ) ( 2), ( 2) [ ( ) ( 2)], 0,1, 4,5 i x i x i x i x i W x i x i i . = + + + = − + = 第三步： 2 2 2 2 2 2 2 2 ( ) ( ) ( 1), ( 4) ( ) ( 1), 0, 2, ( ) ( 3) ( 4), ( 4) ( 3) ( 4), 1,3 X i x i x i X i x i x i i X i x i x i X i x i x i i . = + + + = − + = = + + + + = + − + = 5