Category : Science and Education
Archive   : LONGMATH.ZIP
Filename : LONGMATH.BAS

10 'LONGMATH.BAS: Uses strings and arrays to perform operations on 200-digit
11 'numbers. From BYTE Magazine March 1985 by Peter Rice.
1000 '
1010 DEFINT A-Z
1020 DIM X%(200),Y%(200),Z%(200)
1030 PRINT "Enter a number, up to 200 digits: "
1040 INPUT XX$
1050 WHILE LEFT$(XX$,1)="0":XX$=RIGHT$(XX$,LEN(XX$)-1):WEND
1060 PRINT "Enter an operation: + - * /"
1070 INPUT OP$
1080 PRINT "Enter a second number, up to 100 digits: "
1090 INPUT YY$
1100 WHILE LEFT$(YY$,1)="0":YY$=RIGHT$(YY$,LEN(YY$)-1):WEND
1110 XL=LEN(XX$)
1120 FOR I=1 TO XL
1130 X%(XL-I)=VAL(MID$(XX$,I,1))
1140 NEXT I:X%(200)=XL-1
1150 YL=LEN(YY$)
1160 FOR I=1 TO YL
1170 Y%(YL-I)=VAL(MID$(YY$,I,1))
1180 NEXT I:Y%(100)=YL-1
1190 OPERATION=ASC(OP$)
1200 IF OPERATION=43 THEN GOSUB 10000:GOTO 1260
1210 IF OPERATION=45 THEN GOSUB 11000:GOTO 1260
1220 IF OPERATION=42 THEN GOSUB 12000:GOTO 1260
1230 IF OPERATION=47 THEN GOSUB 13000:GOTO 1260
1240 PRINT"Don't understand operation."
1250 GOTO 1610
1260 IF OPERATION=43 THEN GOTO 1300
1270 IF OPERATION=45 THEN GOTO 1360
1280 IF OPERATION=42 THEN GOTO 1450
1290 IF OPERATION=47 THEN GOTO 1510
1300 ZZ$=" "
1310 FOR I=0 TO Z%(200)
1320 ZZ$=CHR$(Z%(I)+48)+ZZ$
1330 NEXT I
1340 PRINT "The sum is: ":PRINT ZZ$
1350 GOTO 1610
1360 IF Z%(Z%(200))<0 THEN GOTO 1430
1370 ZZ$=" "
1380 FOR I=0 TO Z%(200)
1390 ZZ$=CHR$(Z%(I)+48)+ZZ$
1400 NEXT I
1410 PRINT "The difference is: ":PRINT ZZ$
1420 GOTO 1610
1430 PRINT "The difference is negative."
1440 GOTO 1610
1450 ZZ$=" "
1460 FOR I=0 TO Z%(200)
1470 ZZ$=CHR$(Z%(I)+48)+ZZ$
1480 NEXT I
1490 PRINT "The product is: ":PRINT ZZ$
1500 GOTO 1610
1510 XX$=" "
1520 FOR I=0 TO X%(200)
1530 XX$=CHR$(X%(I)+48)+XX$
1540 NEXT I
1550 ZZ$=" "
1560 FOR I=0 TO Z%(200)
1570 ZZ$=CHR$(Z%(I)+48)+ZZ$
1580 NEXT I
1590 PRINT "The quotient is: ":PRINT ZZ$
1600 PRINT "The remainder is: ":PRINT XX$
1610 FOR I=0 TO 200
1620 X%(I)=0:Z%(I)=0
1630 NEXT I
1640 FOR I=0 TO 100
1650 Y%(I)=0
1660 NEXT I
1670 GOTO 1030
10000 'Addition
10010 IF X%(200)>Y%(100) THEN Z%(200)=X%(200) ELSE Z%(200)=Y%(100)
10020 FOR I=0 TO Z%(200)
10030 Z%(I)=Z%(I)+X%(I)+Y%(I)
10040 IF Z%(I)>=10 THEN Z%(I+1)=Z%(I+1)+1:Z%(I)=Z%(I)-10
10050 NEXT I
10060 IF Z%(Z%(200)+1)>0 THEN Z%(200)=Z%(200)+1
10070 RETURN
11000 'Subtraction
11010 IF X%(200)>Y%(100) THEN N=X%(200) ELSE N=Y%(100)
11020 FOR I=0 TO N
11030 Z%(I)=Z%(I)+X%(I)-Y%(I)
11040 IF Z%(I)<0 THEN Z%(I)=Z%(I)+10:Z%(I+1)=-1
11050 NEXT I
11060 IF Z%(N+1)<0 THEN N=N+1
11070 WHILE Z%(N)=0:IF N=0 THEN GOTO 11080 ELSE N=N-1:WEND
11080 Z%(200)=N
11090 RETURN
12000 'Multiplication
12010 FOR I=0 TO X%(200)
12020 FOR J=0 TO Y%(100)
12030 Z%(I+J)=X%(I)*Y%(J)+Z%(I+J)
12040 A=Z%(I+J)\10
12050 Z%(I+J)=Z%(I+J) MOD 10
12060 Z%(I+J+1)=Z%(I+J+1)+A
12070 NEXT J
12080 NEXT I
12090 INDEX=X%(200)+Y%(100)+1
12100 IF Z%(INDEX)>0 THEN Z%(200)=INDEX ELSE Z%(200)=INDEX-1
12110 RETURN
13000 'Division
13010 IF X%(200)<=Y%(100) THEN AL=Y%(100) ELSE AL=X%(200)
13020 IF X%(AL)>Y%(AL) THEN GOTO 13140
13030 GOSUB 11000
13040 IF Z%(Z%(200))>=0 THEN GOTO 13090
13050 FOR I=0 TO 200
13060 Z%(I)=0
13070 NEXT I
13080 RETURN
13090 FOR I=0 TO 200
13100 X%(I)=Z%(I):Z%(I)=0
13110 NEXT I
13120 Z%(0)=1
13130 RETURN
13140 D=10\(Y%(Y%(100))+1)
13150 IF D=1 THEN GOTO 13340
13160 FOR I=0 TO X%(200)
13170 X%(I)=D*X%(I)
13180 NEXT I
13190 FOR I=0 TO X%(200)
13200 W=X%(I)
13210 X%(I)=W MOD 10
13220 X%(I+1)=X%(I+1)+W\10
13230 NEXT I
13240 IF X%(X%(200)+1)>0 THEN X%(200)=X%(200)+1
13250 FOR I=0 TO Y%(100)
13260 Y%(I)=D*Y%(I)
13270 NEXT I
13280 FOR I=0 TO Y%(100)
13290 W=Y%(I)
13300 Y%(I)=W MOD 10
13310 Y%(I+1)=Y%(I+1)+W\10
13320 NEXT I
13330 IF Y%(Y%(100)+1)>0 THEN Y%(100)=Y%(100)+1
13340 FOR K=X%(200) TO Y%(100) STEP -1
13350 IF X%(K+1)=Y%(Y%(100)) THEN C=9:GOTO 13370
13360 C=(X%(K+1)*10+X%(K))\Y%(Y%(100))
13365 IF Y%(100)=0 THEN GOTO 13400
13370 IF C*Y%(Y%(100)-1)<=(X%(K+1)*10+X%(K)-C*Y%(Y%(100)))*10+X%(K+1) THEN GOTO 13400
13380 C=C+1
13390 GOTO 13370
13400 M=K-Y%(100)
13410 FOR I=0 TO Y%(100)
13420 X%(M+I)=X%(M+I)-C*Y%(I)
13430 NEXT I
13440 FOR I=0 TO Y%(100)
13450 IF X%(M+I)>=0 THEN GOTO 13480
13460 X%(M+I+1)=X%(M+I+1)+X%(M+I)\10-1
13470 X%(M+I)=X%(M+I)+(1-X%(M+I)\10)*10
13480 W=X%(M+I)
13490 X%(M+I)=W MOD 10
13500 X%(M+I+1)=X%(M+I+1)+W\10
13510 NEXT I
13520 IF X%(K+1)>=0 THEN GOTO 13580
13530 FOR I=0 TO Y%(100)
13540 X%(M+I)=X%(M+I)+Y%(I)
13550 IF X%(M+I)>9 THEN X%(M+I+1)=X%(M+I+1)+1:X%(M+I)=X%(M+I)-10
13560 NEXT I
13570 C=C-1
13580 Z%(M)=C
13590 NEXT K
13600 AL=X%(200)-Y%(100)
13610 IF Z%(AL)>0 THEN Z%(200)=AL ELSE Z%(200)=AL-1
13620 BX=Y%(100)
13630 WHILE X%(BX)=0
13650 IF BX=0 THEN GOTO 13670 ELSE BX=BX-1
13660 WEND
13670 X%(200)=BX
13680 FOR I=X%(200) TO 1 STEP -1
13690 W=X%(I)
13700 X%(I)=W\D
13710 X%(I-1)=X%(I-1)+10*(W MOD D)
13720 NEXT I
13730 X%(0)=X%(0)\D
13740 RETURN