10 REM DRAGON CURVE
20 REM SIN, COS IN ARRAYS FOR PI/4 MULTIPL.
30 DIM S(7),C(7)
40 QPI=ATN(1):SQ=SQR(2)
50 FOR I=0 TO 7
60 S(I)=SIN(I*QPI):C(I)=COS(I*QPI)
70 NEXT I
80 LEVEL=15
90 INSIZE=128:REM 2^WHOLE_NUM (LOOKS BETTER)
100 X=112:Y=70
110 ROTQPI=0:RQ=1
120 DIM R(LEVEL)
130 GRAPHIC 2,1
140 GOSUB 160
150 END
160 REM DRAGON
170 ROTQPI=ROTQPI AND 7
180 IF LEVEL>1 THEN GO TO 240
190 YN=S(ROTQPI)*INSIZE+Y
200 XN=C(ROTQPI)*INSIZE+X
210 DRAW ,X,Y TO XN,YN
220 X=XN:Y=YN
230 RETURN
240 INSIZE=INSIZE*SQ/2
250 ROTQPI=(ROTQPI+RQ)AND 7
260 LEVEL=LEVEL-1
270 R(LEVEL)=RQ:RQ=1
280 GOSUB 160
290 ROTQPI=(ROTQPI-R(LEVEL)*2)AND 7
300 RQ=-1
310 GOSUB 160
320 RQ=R(LEVEL)
330 ROTQPI=(ROTQPI+RQ)AND 7
340 LEVEL=LEVEL+1
350 INSIZE=INSIZE*SQ
360 RETURN