10    '***  ALGEBRA AND GEOMETRY PROGRAM
20    '** for the IBM PC...requires 32K and Color/Graphics
30    ON ERROR GOTO 1150
40    CLR
70    REM
80    SCREEN 1,2,0:WIDTH 80:SCNCLR : PRINT "ALGEBRA Graphics Program"
90    PRINT "    Steve VanArsdale"
100   PRINT "Mt.Prospect, Illinois  312-259-7224"
110   PRINT
120   PRINT "SELECT algebra function:"
130   PRINT "A ... for the SINE of X"
140   PRINT "B ... for the COSINE of X"
150   PRINT "C ... for the TANGENT of X"
160   PRINT "D ... for the SECANT of X"
170   PRINT "E ... for the COTANGENT of X"
180   PRINT "F ... for the COSECANT of X"
190   PRINT "G ... for the INVERSE HYPERBOLIC SINE of X"
200   PRINT "H ... for the SQUARE ROOT of X"
210   PRINT " > ";:GETKEY CHOICE$
220   IF CHOICE$ <>"A" AND CHOICE$ <> "a" THEN 230
225   DEF FNFCTN(X)=SIN(X):FCTN$="SIN(X)":GOTO 310
230   '  IF CHOICE$ <>"B" OR CHOICE$ <> "b"  THEN 240
235   '  DEF FNFCTN(X)=COS(X):FCTN$="COSINE(X)":GOTO 310
240   '  IF CHOICE$ <>"C" OR CHOICE$ <> "c" THEN 250
245   '  DEF FNFCTN(X)=TAN(X):FCTN$="TANGENT(X)":GOTO 310
250   '  IF CHOICE$ <>"D" OR CHOICE$ <> "d" THEN 260
255   '  DEF FNFCTN(X)=1/COS(X):FCTN$="SECANT(X)":GOTO 310
260   '  IF CHOICE$ <>"E" OR CHOICE$ <> "e" THEN 270
265   '  DEF FNFCTN(X)=1/TAN(X):FCTN$="COTANGENT(X)":GOTO 310
270   '  IF CHOICE$ <>"F" OR CHOICE$ <> "f" THEN 280
275   '  DEF FNFCTN(X)=1/SIN(X):FCTN$="COSECANT(X)":GOTO 310
280   '  IF CHOICE$ <>"G" OR CHOICE$ <> "g" THEN 290
285   '  DEF FNFCTN(X)=LOG(X+SQR(X*X+1)):FCTN$="INVERSE HYPERBOLIC SINE(X)":GOTO 310
290   '  IF CHOICE$ <>"H" OR CHOICE$ <>"h" THEN 300
295   '  DEF FNFCTN(X)=SQR(ABS(X)):FCTN$="SQ.RT(X)":GOTO 310
300   GOTO 70
310   PRINT "DEPTH OF ";FCTN$;" GRAPH (0 TO 50): ";:INPUT "",DEPTH
320   IF DEPTH < 0 OR DEPTH > 50 THEN GOTO 310
330   SCNCLR:SCREEN 0,2,0 :WIDTH 40
340   '****   GRAPHICS ROUTINE FOR ALGEBRAIC FUNCTIONS ****
350   SCNCLR
360   'SCREEN 1,0:COLOR 0,1
370   C=100:R=100
380   '** AXIS DRAWING ROUTINE
390   GOSUB 1180
400   '** PLOTTING PARAMETERS DISPLAY
410   PRINT AT(1,17); "GRAPH of:"
420   PRINT AT (1,18); FCTN$
430   PRINT AT (1,20); "  X     Y"
440   '** PLOTTING ROUTINE
450   X=0:Y=0:XX=-1:YY=FNFCTN(XX):DRAW (100,100)
460   FOR X = -1 TO 7 STEP .1
470   PRINT AT (1,21);:PRINT USING "##.##";X
480   REM
490   Y = FNFCTN(X)
500   YLIMIT=98-30*Y : DEPTHLIMIT=100-30*Y-DEPTH : IF YLIMIT < 0 OR YLIMIT > 200 OR DEPTHLIMIT < 0 THEN GOTO 570
510   ON ERROR GOTO 1270
520   PRINT AT (7,21);:PRINT USING "##.##";Y
530   DRAW (20*X+100,100-30*Y),2
540   IF DEPTH <> 0 THEN DRAW (20*X+101,99-30*Y TO 20*X+100+DEPTH,100-30*Y-DEPTH),1
550   DRAW (20*XX+100,100-30*YY TO 20*X+100,100-30*Y),2
560   IF DEPTH <> 0 THEN DRAW (20*XX+100+DEPTH,100-30*YY-DEPTH TO 20*X+100+DEPTH,100-30*Y-DEPTH),2
570   XX=X:YY=Y
580   NEXT X
590   GOSUB 1180
600   PRINT AT (1,23); "ENTER  X  TO EXIT";:VALUE$=INPUT$(1)
610   IF VALUE$ <> "X" AND VALUE$ <> "x" THEN GOTO 70 ELSE SCNCLR
620   '****  SPECIAL EXIT DISPLAY ****
630   '** AXIS DRAWING SUBROUTINE
640   GOSUB 1180
650   '** PLANE GRID DRAWING ROUTINE
660   FOR X = 10 TO R-10 STEP 10
670   DRAW (C+X,R-X TO 105+C+X,R-X),1
680   DRAW (C+X,R-X TO C+X,0),1
690   DRAW (C,R-X TO 195-X,5),1
700   DRAW (C+X,R TO 195+X,5),1
710   NEXT X
720   PRINT AT (22,1); " Z axis"
730   '** HOOP ROUTINE
740   CIRCLE (160,90),50,1
750   'FOR I = 1 TO 20 STEP
760   'CIRCLE STEP (1,-1),50,1
770   'NEXT I
780   'CIRCLE (160,90),50,1
790   '** ELLIPTICAL TUBE ROUTINE
800   'CIRCLE (155,90),25,1
810   'FOR I = 1 TO 35
820   'CIRCLE STEP (1,1),25,1
830   'NEXT I
840   'CIRCLE STEP (1,1),25,1
850   CIRCLE (155,90),25,.5
860   'FOR I = 1 TO 20
870   'CIRCLE STEP (1,-1),24,1,,,.5
880   'NEXT I
890   CIRCLE (155,90),25,.5
900   '***  CONE ROUTINE
910   CIRCLE (45,55),38,3
920   'FOR I = 1 TO 38
930   'CIRCLE STEP (+1,-1),38-I,(I MOD 2)+2,,,1
940   'NEXT I
950   CIRCLE (45,55),38,1
960   '**  GLOBE ROUTINE
970   CIRCLE (245,170),1,2
980   'FOR I = 1 TO 10 STEP 1
990   'CIRCLE STEP (+I/4,-I/4),I*4,1,,,1
1000  'NEXT I
1010  'FOR I = 10 TO 0 STEP -1
1020  'CIRCLE STEP (+I/4,-I/4),I*4,2,,,1
1030  'NEXT I
1040  DRAW  (TO 245,170),3
1050  '** PYRAMID ROUTINE
1060  'DRAW "BM10,150;C1;E30;F30;L60"
1070  'DRAW "BM+30,-28;D13"
1080  DRAW (40,135 TO 11,149),1
1090  DRAW (40,135 TO 69,149),1
1100  '** CUBE ROUTINE
1110  'DRAW "BM265,85;C3;U30;R30;D30;L30"
1120  'DRAW "BM+20,-20;C3;U30;R30;D30;L30"
1130  'DRAW "C3;G20;BM+30,0;E20;BM+0,-30;G20;BM-30,0;E20"
1140  PRINT AT (1,25); "BYE.";
1150  '**** TERMINATION LOGIC
1160  SCNCLR: PRINT "ALGEBRA Program Terminated."
1170  END
1180  '****  AXIS DRAWING SUBROUTINE ****
1190  '****  AXIS DRAWING SUBROUTINE ****
1200  DRAW (C,0 TO C,199),6
1210  DRAW (90,110 TO 200,0),6
1220  DRAW (0,R TO 319,R),6
1230  PRINT AT (1,13); "X axis"
1240  PRINT AT (10,2); "Y axis"
1250  PRINT AT (22,1); " Z axis"
1260  RETURN
1270  '****  CALCULATION ERROR HANDLER
1280  RESUME 390
1290  SCNCLR : PRINT "ALGEBRA Graphics Program"