10 PRINT : PRINT "EXAMPLE 5.3-3 DRAINAGE  OF  RESERVOIR--2ND ORDER  RUNGE-KUTTA": PRINT
20 DEF FNQ (YD, TD) = SQR(C1 * YD / (K1 + K2 * TD + K3 * TD ^ 2)) / (A1 + A2 * YD + A3 * YD ^ 2)
30 DEFINT I: READ A1, A2, A3, K1, K2, K3, Y, TMAX, PI, H, G, D
40 DATA 4., .1, .01, 1.5, .04, .0001, 20!, 300!, 3.1416, 1., 9.806001, .15
50 PRINT : PRINT "A1,A2,A3,K1,K2,K3="; A1; A2; A3; K1; K2; K3
60 PRINT "Y,TMAX,PI,H,G,D="; Y; TMAX; PI; H; G; D: PRINT
70 C1 = 2! * G * (.25 * PI * D ^ 2) ^ 2: T = 0!: I = 0: A = A1 + Y * (A2 + A3 * Y): Q = FNQ(Y, T) * A: K = K1
80 PRINT "  T,s    Y,m    Q,m^3/s AREA, m^2   K": PRINT
90 PRINT USING "###.### "; T; Y; Q; A; K
100 IF T >= TMAX THEN GOTO 150
110 I = I + 1: U1 = -H * FNQ(Y, T): U2 = -H * FNQ(Y + U1, T + H): Y = Y + .5 * (U1 + U2): T = T + H
120 A = A1 + A2 * Y + A3 * Y ^ 2: Q = FNQ(Y, T) * A: K = K1 + T * (K2 + K3 * T)
130 IF I MOD 30 = 0 THEN 90 ELSE GOTO 110
140 IF T < TMAX THEN 110 ELSE STOP
150 PRINT : PRINT "T, TMAX ="; T; TMAX