10! ***FORRESTER MODEL, WORLD DYNAMICS***

20 &:&"WORLD DYNAMICS MODEL"

30 &"AFTER THE FIRST RUN, TYPE 'RUNNH' FOR A SECOND, THIRD, ETC.":&

40 Z9$="KB:": INPUT"MODEL ";X$

50 DIM G(100)

60 READ J8

70 MAT READ G$(J8)

80 MAT READ M(J8)

90 G$(0)=" "

100 OPEN Z9$ FOR OUTPUT AS FILE 1

110 READ S9

120 READ P,N,C,A,W   ! INITIALIZE LEVELS

130 READ T0,T1,T2,T3,T4  ! TIME PARAMETERS (FROM,TO,STEP,SWITCH,PRINT

140 READ B7,D7,N7,F7,C7,X7,W7  ! SWITCH PARAMETERS

150 X8=X7

0 INPUT"BR,DR ";X,Y

170 B8=B7*X

180 D8=D7*Y

190 INPUT"NR,POL ";X,Y

200 N8=N7*X

210 W8=W7*Y

220 INPUT"FC,CI ";X,Y

230 F8=F7*X

240 C8=C7*Y

250 DIM T(22,10)

260 READ I9,J9   ! TABLE

270 FOR I=1 TO I9

280 FOR J=0 TO J9

290 READ T(I,J)

300 IF T(I,J)<0 THEN 320 

310 NEXT J

320 NEXT I

330 DEF FNC(X,Y)

340 FNC=X

350 IF T<T3 THEN 370 

360 FNC=Y

370 FNEND

380 DEF FNR(X)=INT(X*100+.5)/100

390 DEF FNT(I,X,M,S)

400 IF X>=0 THEN 430 

410 FNT=T,0)

420 GOTO 490 

430 IF X<M THEN 460 

440 FNT=T(I,M/S)

450 GOTO 490 

460 Z1=X/S

470 Z2=INT(Z1)

480 FNT=T(I,Z2)+(Z1-Z2)*(T(I,Z2+1)-T(I,Z2))

490 FNEND

500 GOSUB 1370 

510 FOR T=T0 TO T1 STEP T2

520 W1=W/3.6E9   ! CYCLE

530 F1=FNT(1,W1,60,10)

540 W2=FNT(2,W1,60,10)

550 W9=W/W2

560 C1=C/P

570 C2=C1*A/.3

580 F2=FNT(3,C2,6,1)

590 P1=P/(135E6*26.5)

600 B1=FNT(4,P1,5,1)

610 D1=FNT(5,P1,5,1)

620 F3=FNT(6,P1,5,1)

630 F=F2*F3*F1*FNC(F7,F8)/1

6402=FNT(7,F,4,1)

650 C3=FNT(8,F,2,.5)

660 Q1=FNT(9,F,4,1)

670 N1=N/9E11

680 N2=FNT(10,N1,1,.25)

690 C4=C1*(1-A)*N2/(1-.3)

700 M=C4/1

710 B3=FNT(11,M,5,1)

720 Q2=FNT(12,M,5,1)

730 C5=FNT(13,Q2,2,.5)

740 N3=FNT(14,M,10,1)

750 Q3=FNT(15,W1,60,10)

760 Q4=FNT(16,P1,5,.5)

770 Q=1*Q2*Q4*Q1*Q3

780 A=A+(T2/15)*(C3*C5-A)

790 W3=FNT(17,C1,5,1)

800 W0=P*FNC(W7,W8)*W3

810 W=W+T2*(W0-W9)

820 L=C*FNC(X7,X8)

830 C6=FNT(18,M,5,1)

840 G=P*C6*FNC(C7,C8)

850 C=C+*(G-L)

860 B4=FNT(19,W1,60,10)

870 D2=FNT(20,F,2,.25)

880 D3=FNT(21,W1,60,10)

890 D4=FNT(22,M,5,.5)

900 D=P*FNC(D7,D8)*D4*D3*D2*D1

910 R=P*FNC(N7,N8)*N3

920 N=N-T2*R

930 B=P*FNC(B7,B8)*B2*B3*B1*B4

940 P=P+T2*(B-D)

950 T9=T/T4

960 IF ABS(INT(T9)-T9)>1E-5 THEN 990 

970 GOSUB 1300 

980 GOSUB 1020 

990 NEXT T

1000 GOSUB 1370 

1010 GOTO 1660 

1020 MAT G=ZER   ! GRAPHIC OUTPUT

1030 G(0)=0

1040 FOR J=1 TO J8

1050 M=M(J)

1060 S=M/S9

1070 X=P(J)
1080 IF X>=0 THEN 1120 

1090 &#1

1100 &#1,G$(J);" TURNED NEGATIVE"

1110 GOTO 1660 

1120 IF X>M THEN 1150 

1130 Y=FNR(X/S)

1140 G(Y)=J

1150 NEXT J

1160 T=T0+(P3-1)*T4

1170 IF T/20<>INT(T/20) THEN 1190 

1180 &#1,T;

1190 &#1,TAB(8);

1200 GOSUB 1260 

1210 FOR J=0 TO J9

1220 &#1,G$(G(J));

1230 NEXT J

1240 &#1

1250 RETURN

1260 FOR J9=S9 TO 0 STEP -1  ! FIND END OF LINE

1270 IF G(J9)>0 THEN 1290 

1280 NEXT J9

1290 RETURN

1300 P3=P3+1  ! SAVE RESTS

1310 P(1)=FNR(P/1E9)

1320 P(2)=FNR(W1)

1330 P(3)=FNR(C/1E9)

1340 P(4)=FNR(Q)

1350 P(5)=FNR(N/1E11)

1360 RETURN

1370 & FOR K=1 TO 5: RETURN

1380 DATA 5, P,W,C,Q,N,8,40,20,2,10

1390 DATA 60

1400 DATA 1.65E9,9E11,4E8,.2,2E8

1410 DATA 1900,2100,.5,1970,5

1420 DATA .04,.028,1,1,.05,.025,1

1430 DATA 22,10

1440 DATA 1.02,.9,.65,.35,.2,.1,.05,-1

1450 DATA .6,2.5,5,8,11.5,15.5,20,-1

1460 DATA .5,1,1.4,1.7,1.9,2.05,2.2,-1

1470 DATA 1.05,1,.9,.7,.6,.55,-1

14 DATA .9,1,1.2,1.5,1.9,3,-1

1490 DATA 2.4,1,.6,.4,.3,.2,-1

1500 DATA 0,1,1.6,1.9,2,-1

1510 DATA 1,.6,.3,.15,.1,-1

1520 DATA 0,1,1.8,2.4,2.7,-1

1530 DATA 0,.15,.5,.85,1,-1

1540 DATA 1.2,1,.85,.75,.7,.7,-1

1550 DATA .2,1,1.7,2.3,2.7,2.9,-1

1560 DATA .7,.8,1,1.5,2,-1

1570 DATA 0,1,1.8,2.4,2.9,3.3,3.6,3.8,3.9,3.95,4

1580 DATA 1.04,.85,.6,.3,.15,.05,.02,-1

1590 DATA 2,1.3,1,.75,.55,.45,.38,.3,.25,.22,.2

1600 DATA .05,1,3,5.4,7.4,8,-1

1610 DATA .1,1,1.8,2.4,2.8,3,-1

10 DATA 1.02,.9,.7,.4,.25,.15,.1,-1

1630 DATA 30,3,2,1.4,1,.7,.6,.5,.5,-1

1640 DATA .91,1.3,2,3.2,4.8,6.8,9.2,-1

1650 DATA 3,1.8,1,.8,.7,.6,.53,.5,.5,.5,.5

1660 &#1,CHR$(26): CLOSE 1

1670 END