PROGRAM von_Koch_curve   !© W.van Duyn 7th MAY 2004
SET MODE "color"
SET WINDOW 0,1199,0,903
SET COLOR 16
BOX AREA 0,1199,0,903
FLOOD 1,1
SET BACKGROUND COLOR "black"
SET COLOR "white"
PRINT" sierpinski carpet I.F.S."
PRINT" © W.VanDuyn 7th May 2004 "
LET x=1
LET y=1
LET a=0
LET f=900
RANDOMIZE
LET r=3
FOR n= 1 TO 500000
LET a = INT(RND*4)+1
IF a =1 THEN
LET x1=x/r
LET y1=y/r
END IF
IF a=2 THEN
LET x1=x/6-0.289*y+1/r
LET y1=0.289*x+y/6
END IF
IF a =3 THEN
LET x1=x/(2*r)+0.289*y+0.500
LET y1=-0.289*x+y/6+0.289
END IF
IF a=4 THEN LET x1=x/r+2/r
LET y1=y/r
END IF
SET COLOR MIX (a+100) 1,1-a/4,a/4
SET COLOR MIX (a+200) a/4,1,1-a/4
IF mod(a,2) = 0 THEN SET COLOR a+100
IF mod(a,2) = 1 THEN SET COLOR a+200
LET x=x1
LET y=y1
IF n>10 THEN PLOT f*x+600-f/2,450+f*y-150
NEXT n
END