4.减法运算 R u =u i=i=0 R 12 u-u 2 R R R+ r 解得 R R R (1+-) r+R R R R R=R,,R=R uo=(u2 -WiR4. 减法运算 +_uo _+ + R 2 R f i-u+ u￾R1 R3 ui1 ui2 i 1 if u - = u + i- = i+=0 i 1= i f 2 3 3 R R R u u u + = = − + i 2 R f u u R u u i o 1 i 1 1 − = − = − − 解得： 1 1 2 3 1 3 0 1 RR u RR R R R u u f f i 2 i ( + ) − + = 1 1 2 3 0 1 RR R R R R u u u f , ( ) 当 = f = = i 2 − i