SCREEN 13
wide% = 320
tall% = 200
size = 1
pix = 1
'default window is (-2.1, -1.2)-(.8, 1.2)
xmin = -.1
ymin = -1
xmax = .2
ymax = -.7
WINDOW (xmin * size, ymin * size)-(xmax * size, ymax * size)
t = TIMER
xstep = (xmax - xmin) / wide%
ystep = (ymax - ymin) / tall%
FOR x = xmin TO xmax STEP xstep
 
  FOR y = ymin TO ymax STEP ystep
    r = x
    s = y
    m = 1

    DO
      xx = r ^ 2 - s ^ 2 + x
      s = 2 * r * s + y
      r = xx
      m = m + 1
      IF m > 40 THEN EXIT DO
    LOOP WHILE (r ^ 2 + s ^ 2) < 6400
   
 '   SELECT CASE m
 '     CASE 1 TO 3: col = 1    'dark blue
 '     CASE 4 TO 6: col = 12   'orange
 '     CASE 7 TO 9: col = 9    'light blue
 '     CASE 10 TO 12: col = 4  'red
 '     CASE 13 TO 15: col = 14 'yellow
 '     CASE 16 TO 20: col = 3  'purple
 '     CASE 21: col = 0        'black
 '   END SELECT
    col = m
    IF col = 41 THEN col = 0
    PSET (x, y), col
    PSET (x, -y), col
    IF INKEY$ = CHR$(27) THEN END
  NEXT y
NEXT x
PRINT USING "\    \###.##"; "Time: "; TIMER - t

    Source: geocities.com/siliconvalley/park/3889

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