∑P(5,m,41)c0sa1+Q(5,n,5)os月 +R(5;,7,5)c0sy;|S ∑|P(5,m,41)AS)+Q(,7,5)AS) +R(5;,,57)(△S) 3.取极限λ-0取极限得到流量Φ的精确值.i i i i i i i i i n i i i i i R S P Q +  =  + = ( , , )cos ] [ ( , , )cos ( , , )cos 1             i i i i x y yz i i i i x z n i i i i i R S P S Q S ( , , )( ) [ ( , , )( ) ( , , )( ) 1 +  =   +  =          3.取极限  → 0取极限得到流量的精确值