SUBROUTINE BOX
	REAL X(4),Y(4),XV(4),YV(4)
	COMMON /DPYBUF/ IDBUF(2000)
C
C
C
	DATA X/-5.,-5.,5.,5./,Y/-4.,-6.,4.,6./,
	+	XV/.2,-.2,.16,-.1/,YV/.1,-.3,.15,.13/
C
C
C
	CALL INIT
	CALL SCAL(-13.4375,-10.,13.4375,16.7)
	CALL APNT(-10.,-10.,0,-5)
	CALL LVECT(0.,20.)
	CALL LVECT(20.,0.)
	CALL LVECT(0.,-20.)
	CALL LVECT(-20.,0.)
C
C
C
	DO 100 I=1,500
	CALL SUBP(1)
	CALL APNT(X(1),Y(1),0,-5)
	CALL LVECT(X(2)-X(1),Y(2)-Y(1))
	CALL LVECT(X(3)-X(2),Y(3)-Y(2))
	CALL LVECT(X(4)-X(3),Y(4)-Y(3))
	CALL LVECT(X(1)-X(4),Y(1)-Y(4))
	CALL LVECT(X(3)-X(1),Y(3)-Y(1))
	CALL APNT(X(2),Y(2),0,-5)
	CALL LVECT(X(4)-X(2),Y(4)-Y(2))
	CALL ESUB
	DO 40 J=1,4
	X(J) = X(J) + XV(J)
	Y(J) = Y(J) + YV(J)
	IF (X(J).LE.-10.) GOTO 10
	IF (X(J).LT.10.) GOTO 20
	X(J) = 9.999
15	XV(J) = -XV(J)
	GOTO 20
10	X(J) = -9.999
	GOTO 15
20	IF (Y(J).LE.-10.) GOTO 30
	IF (Y(J).LT.10.) GOTO 5
	Y(J) = 9.999
50	YV(J) = -YV(J)
	GOTO 5
30	Y(J) = -9.999
	GOTO 50
5	CONTINUE
40	CONTINUE
	CALL ERAS(1)
	CALL CMPRS
	KVAL = IPOT0()
	IF (KVAL.NE.0) CALL SLEEP(0,0,0,KVAL)
100	CONTINUE
	RETURN
	END