100 REM projective transformation of a circle
110 DECLARE EXTERNAL PICTURE circle
120 DIM T(4,4)
130 MAT READ T
140 DATA 1, 0, 0, 0.1
150 DATA 0, 1, 0,-0.1
160 DATA 0, 0, 1, 0
170 DATA 2, 2, 0, 1 
180 SET WINDOW -100, 100, -100, 100  
190 DRAW axes(10,10)
200 FOR a=1 TO 10
210    SET LINE COLOR a
220    DRAW circle WITH SCALE(a)*T
230 NEXT a
240 END                                                        
250 EXTERNAL PICTURE circle  
260 OPTION ANGLE DEGREES
270 FOR t=0 TO 360 
280    PLOT LINES : COS(t),SIN(t);
290 NEXT t
300 END PICTURE
