10 LET level=15: LET insize=120
20 LET x=80: LET y=70
30 LET sq=SQR (2): LET qpi=PI/4
40 LET rotation=0: LET rq=1
50 DIM r(level)
60 GO SUB 70: STOP
70 REM Dragon
80 IF level>1 THEN GO TO 140
90 LET yn=SIN (rotation)*insize+y
100 LET xn=COS (rotation)*insize+x
110 PLOT x,y: DRAW xn-x,yn-y
120 LET x=xn: LET y=yn
130 RETURN
140 LET insize=insize/sq
150 LET rotation=rotation+rq*qpi
160 LET level=level-1
170 LET r(level)=rq: LET rq=1
180 GO SUB 70
190 LET rotation=rotation-r(level)*qpi*2
200 LET rq=-1
210 GO SUB 70
220 LET rq=r(level)
230 LET rotation=rotation+rq*qpi
240 LET level=level+1
250 LET insize=insize*sq
260 RETURN