10 ' modified Guilloche pattern
20 CLEAR ALL
30 SCREEN 6
40 xr=170
50 yr=150
60 cx=640
70 cy=400
80 FOR sc=1 TO 150 STEP 2
90     FOR ang=1 TO 360*2
100         x=(xr+sc*SIN(10*ang))*COS(ang)
110         y=(yr+sc*SIN(7*ang))*SIN(ang)
120         PLOT cx+x,cy+y
130     NEXT
140 NEXT
