Attrattori instabili

0 rem per commodore 128
5 color 0, 2
6 color 1, 5
8 color 2, 10
9 color 3, 15:color 4,1:color 5,12

10 graphic 1, 1
12 fast: rem remmare questa e la riga 220 se si vuole vedere la costruzione
15 a=1.11:y=0:sn=sin(a):cs=cos(a)
18 xi=-1.2:xf=1.2:yi=-1.2:yf=1.2
20 sx=(xf-xi)/320:sy=(yf-yi)/200
30 for xc=xi to xf step sx:y=xc:x=xc:i=1
150 do while i <= 200
158 if x > 1.0E+15 then exit
165 yx = y-x*x
170 xx=x*cs-yx*sn
180 y=x*sn+yx*cs
190 x=xx
201 px=160+int(x/sx):py=100-int(y/sy)
203 if px>0andpx<321andpy>0and py<201 then draw 1, px, py
204 i=i+1
206 loop
211 next
220 slow
230 getkey a$