*20
// SUBROUTINE ARCTAN.
	 
/ENTER WITH TANGENT IN FAC.
/EXIT WITH ANGLE IN RADIANS IN FAC.
	 
/FORMULA:
/ARCTANX=PI\4 + C1(XFAC) + C3(XFAC)^3
/             + C5(XFAC)^5
	 
/WHERE XFAC= (X-1)\(X+1)
/      0<X,<INFINITY
/      C1=+.995354
/      C3=-.288679
/      C5=+.079331
/    PI\4=+.7854
	 
	 
ARCTAN,	FADD
	FP1
	ADD 0
	STC ARCTX
	STORE
	XFAC		/X+1
	LOAD
	XFAC
	FSUB
	FP2		/X-1
	FDIV
	XFAC
	STORE
	XFAC		/X-1\X+1
	 
	LOAD
	C5
	JMP MULT
	FADD
	C3
	JMP MULT
	FADD
	C1
	JMP MULT+2
	FADD
	PID4
ARCTX,	0		/LEAVE
	 
C1,	0000		/+.995354
	3766
	3703
	 
C3,	7776		/-.288679
	5541
	4442
	 
C5,	7774		/+.079331
	2423
	6045
	 
PID4,	0000		/PI\4 OR .7854
	3110
	3776
	 
FP2,	2
	2000
	0
	 
MULT,	FMUL
	XFAC
	FMUL
	XFAC
	JMP 0
	 
XFAC,	0
	0
	0
//END SUBROUTINE ARCTAN.
/NOV 73
/FHD