SUBROUTINE BN3(X,Y,ANG,ELD,FI,HEL,PSI)
	DIMENSION FIC(2),DK(2)
	REAL LAM,M,KC,KIC
	LAM=PSI-FI
	M=SIN(PSI/2.)
	CALL CEL1(KC,M,IER)
	CALL CEL2(EC,M,IER)
	TOL=.1E-5
	I1=0
	K1=1
	I=1
	FIC(I)=0.0
	GO TO 2
1	ELDP=ELD
	IF(ELD-EL) 6,7,8
7	RETURN
8	XX=X
	ELDP=2.*HEL-ELD
6	I=2
	FIC(I)=.5*FI
2	ARG=(SIN((FIC(I)+LAM)*.5))/M
	IF(ABS(ARG).GT.1.) ARG=SIGN(1.0,ARG)
	THETA=ASIN(ARG)
	CALL ELI1(KIC,THETA,M)
	CALL ELI2(EIC,THETA,M)
	DK(I)=KC-KIC
	DE=EC-EIC
	EL=HEL*DK(I)/DK(1)
	AK=(2.*DE/DK(I))-1.
	BK=(2.*M*COS(THETA))/DK(I)
	X=EL*(AK*COS(LAM)+BK*SIN(LAM))
	Y=EL*(BK*COS(LAM)-AK*SIN(LAM))
	ANG=FIC(I)
	IF(I-1) 3,1,3
3	CALL ITER8(1,K1,ANG,XM1,EL,YM1,ELDP,DF,I1,TOL)
	IF(I1) 5,4,5
4	FIC(I)=ANG+DF
	IF(FIC(I).GT.FI) FIC(I)=FI-DF/(100.*K1)
	GO TO 2
5	IF(ELD.LT.HEL) RETURN
	X=2.*XX-X
	ANG=-ANG
	RETURN
	END