DECLARE SUB init ()
DECLARE SUB pp (x1, y1, x2, y2, c!)
DIM SHARED mul

mul = 50        '<< scale
init

ox = -320 / mul
oy = 0

FOR x = -320 / mul TO 320 / mul STEP 1 / mul


t = x ^ 3 - (3 * x)     '<< Type your formula there


pp x, t, ox, tol, 10
y = (t - tol) * mul
tol = t

pp x, y, ox, oy, 14
ox = x
oy = y
NEXT x

SUB init
SCREEN 12

FOR x = -320 TO 320
IF x / mul = x \ mul THEN LINE (x + 320, 0)-(x + 320, 479), 1
NEXT x

FOR y = -240 TO 240
IF y / mul = y \ mul THEN LINE (0, y + 240)-(639, y + 240), 1
NEXT y

FOR x = -320 TO 320
IF x / (mul * 5) = x \ (mul * 5) THEN LINE (x + 320, 0)-(x + 320, 479), 4
NEXT x

FOR y = -240 TO 240
IF y / (mul * 5) = y \ (mul * 5) THEN LINE (0, y + 240)-(639, y + 240), 4
NEXT y



LINE (0, 240)-(639, 240), 3
LINE (320, 0)-(320, 479), 3
END SUB

SUB pp (x, y, x1, y1, c)

x2 = (x * mul) + 320
y2 = 240 - (y * mul)
x3 = (x1 * mul) + 320
y3 = 240 - (y1 * mul)
IF x2 < 0 THEN GOTO 1
IF y2 < 0 THEN GOTO 1
IF x2 > 639 THEN GOTO 1
IF y2 > 479 THEN GOTO 1
IF x3 < 0 THEN GOTO 1
IF y3 < 0 THEN GOTO 1
IF x3 > 639 THEN GOTO 1
IF y3 > 479 THEN GOTO 1
LINE (x2, y2)-(x3, y3), c
1
END SUB