1000 REM LOGISTIC EQUATION
1010 DEFDBL A-Z                 'Use double precision
1030 SM% = 12                   'Assume VGA graphics
1190 GOSUB 1300                 'Initialize
1200 GOSUB 1500                 'Set parameters
1210 GOSUB 1700                 'Iterate equations
1220 GOSUB 2100                 'Display results
1230 GOSUB 2400                 'Test results
1240 ON T% GOTO 1190, 1200, 1210
1250 CLS
1260 END

1300 REM Initialize
1320 SCREEN SM%                 'Set graphics mode
1350 WINDOW (-.1, -.1)-(1.1, 1.1)
1360 CLS
1420 RETURN

1500 REM Set parameters
1510 X = .05                    'Initial condition
1560 R = 4                      'Growth rate
1570 T% = 3
1590 LINE (-.1, -.1)-(1.1, 1.1), , B
1630 RETURN

1700 REM Iterate equations
1720 XNEW = R * X * (1 - X)
2030 RETURN

2100 REM Display results
2300 PSET (X, XNEW)             'Plot point on screen
2320 RETURN

2400 REM Test results
2490 IF LEN(INKEY$) THEN T% = 0 'Respond to user key stroke
2510 X = XNEW                   'Update value of X
2550 RETURN