0 CLS
10 XMIN=-1.5:XMAX=2:YMIN=-1.5:YMAX=1.5
20 NX%=SCREENWIDTH(0):NY%=SCREENHEIGHT(0)
30 Y=YMIN
40 HX=(XMAX-XMIN)/NX%
50 HY=(YMAX-YMIN)/NY%
60 FOR J%=0 TO NY%
70 X=XMIN
80 FOR I%=0 TO NX%
90 GOTO 400
100 SETCOLOR K%,K%,K%
120 PLOT I%,J%
150 X=X+HX
160 NEXT I%
170 Y=Y+HY
180 NEXT J%
190 GOTO 500
400 X1=Y1=0:K%=100
410 X2=X1*X1:Y2=Y1*Y1:XY=X1*Y1
420 X1=X2-Y2+X:Y1=2*XY+Y:R=X2+Y2
430 K%=K%-1
440 IF R<4 AND K%>0 THEN GOTO 410
450 V=K%:K%=(V/100)*225
460 GOTO 100
500 IF FIRE(0) THEN END
510 GOTO 500