Ux =y W11X1+12x2+…+41,m-2xn-2+41,n-1xn-1+ uinXn y1, u22X2+…+l2,n-2Xm-2+l2,n-1Xn-1+l2mXn=y2, un-2,n-2Xn-2+un-2,n-1Xn-1 un-2nXn yn-2 un-1,n-1Xn-1 un-1nXn yn-1, ln,nxn=yn· -(-三小