### FILE="Main.annotation"
## Copyright:   Public domain.
## Filename:	PLANETARY_INERTIAL_ORIENTATION.agc
## Purpose:     Part of the source code for Colossus build 237.
##              This is for the Command Module's (CM) Apollo Guidance
##              Computer (AGC), for Apollo 8.
## Assembler:   yaYUL
## Contact:     Jim Lawton <jim DOT lawton AT gmail DOT com>
## Website:     www.ibiblio.org/apollo/index.html
## Page Scans:  www.ibiblio.org/apollo/ScansForConversion/Colossus237/
## Mod history: 2011-04-13 JL	Adapted from corresponding Colossus 249 file.
##		2017-01-01 RSB	Proofed comment text using octopus/ProoferComments,
##				and fixed errors found.
##		2017-03-16 RSB	Comment-text fixes identified in 5-way
##				side-by-side diff of Luminary 69/99/116/131/210.

## Page 1210
# ..... RP-TO-R SUBROUTINE .....
# SUBROUTINE TO CONVERT RP (VECTOR IN PLANETARY COORDINATE SYSTEM,EITHER
#  EARTH-FIXED OR MOON-FIXED) TO R (SAME VECTOR IN THE BASIC REF. SYSTEM)

#  R=MT(T)*(RP+LPXRP)    MT= M MATRIX TRANSPOSE

# CALLING SEQUENCE
#  L       CALL
#  L+1            RP-TO-R

# SUBROUTINES USED
#  EARTHMX,MOONMX,EARTHL

#    ITEMS AVAILABLE FROM LAUNCH DATA
#     504LM= THE LIBRATION VECTOR L OF THE MOON AT TIME TIMSUBL,EXPRESSED
#     IN THE MOON-FIXED COORD. SYSTEM   RADIANS  B0
#       ITEMS NECESSARY FOR SUBR. USED (SEE DESCRIPTION OF SUBR.)

# INPUT
#  MPAC= 0 FOR EARTH,NON-ZERO FOR MOON
#  0-5D= RP VECTOR
#  6-7D= TIME

# OUTPUT
#  MPAC= R VECTOR METERS B-29 FOR EARTH, B-27 FOR MOON

		SETLOC	PLANTIN
		BANK

		COUNT*	$$/LUROT

RP-TO-R		STQ	BHIZ
			RPREXIT
			RPTORA
		CALL			# COMPUTE M MATRIX FOR MOON
			MOONMX		# LP=LM FOR MOON  RADIANS B0
		VLOAD
			504LM
RPTORB		VXV	VAD
			504RPR
			504RPR
		VXM	GOTO
			MMATRIX		# MPAC=R=MT(T)*(RP+LPXRP)
			RPRPXXXX	# RESET PUSHLOC TO 0 BEFORE EXITING
RPTORA		CALL			# EARTH COMPUTATIONS
			EARTHMX		# M MATRIX B-1
		CALL
			EARTHL		# L VECTOR RADIANS B0
		MXV	VSL1		# LP=M(T)*L  RAD B-0
			MMATRIX
## Page 1211
		GOTO
			RPTORB

## Page 1212
# ..... R-TO-RP SUBROUTINE .....
# SUBROUTINE TO CONVERT R (VECTOR IN REFERENCE COORD. SYSTEM) TO RP
#  (VECTOR IN PLANETARY COORD SYSTEM) EITHER EARTH-FIXED OR MOON-FIXED

#  RP=M(T)*(R-LXR)

# CALLING SEQUENCE
#  L       CALL
#  L+1            R-TO-RP

# SUBROUTINES USED
#  EARTHMX,MOONMX,EARTHL

# INPUT
#  MPAC= 0 FOR EARTH,NON-ZERO FOR MOON
#  0-5D= R VECTOR
#  6-7D= TIME

#    ITEMS AVAILABLE FROM LAUNCH DATA
#     504LM= THE LIBRATION VECTOR L OF THE MOON AT TIME TIMSUBL,EXPRESSED
#     IN THE MOON-FIXED COORD. SYSTEM   RADIANS B0
#       ITEMS NECESSARY FOR SUBROUTINES USED (SEE DESCRIPTION OF SUBR.)

# OUTPUT
#  MPAC=RP VECTOR METERS B-29 FOR EARTH, B-27 FOR MOON

R-TO-RP		STQ	BHIZ
			RPREXIT
			RTORPA
		CALL
			MOONMX
		VLOAD	VXM
			504LM		# LP=LM
			MMATRIX
		VSL1			#  L=MT(T)*LP  RADIANS B0
RTORPB		VXV	BVSU
			504RPR
			504RPR
		MXV			# M(T)*(R-LXR) B-2
			MMATRIX
RPRPXXXX	VSL1	SETPD
			0D
		GOTO
			RPREXIT
RTORPA		CALL			# EARTH COMPUTATIONS
			EARTHMX
		CALL
			EARTHL
		GOTO			# MPAC=L=(-AX,-AY,0) RAD B-0
			RTORPB

## Page 1213
# ..... MOONMX SUBROUTINE .....
# SUBROUTINE TO COMPUTE THE TRANSFORMATION MATRIX M FOR THE MOON

# CALLING SEQUENCE
#  L       CALL
#  L+1            MOONMX

# SUBROUTINES USED
#  NEWANGLE

# INPUT
#  6-7D= TIME
#    ITEMS AVAILABLE FROM LAUNCH DATA
#     BSUBO,BDOT
#     TIMSUBO,NODIO,NODDOT,FSUBO,FDOT
#     COSI= COS(I) B-1
#     SINI= SIN(I) B-1
#       I  IS THE ANGLE BETWEEN THE MEAN LUNAR EQUATORIAL PLANE AND THE
#       PLANE OF THE ECLIPTIC  (1 DEGREE 32.1 MINUTES)

# OUTPUT
#  MMATRIX= 3X3 M MATRIX B-1   (STORED IN VAC AREA)

MOONMX		STQ	SETPD
			EARTHMXX
			8D
		AXT,1			# B REQUIRES SL 0, SL 5 IN NEWANGLE
			5
		DLOAD	PDDL		# PD 10D            8-9D=BSUBO
			BSUBO		#                   10-11D=BDOT
			BDOT
		PUSH	CALL		# PD 12D
			NEWANGLE	# EXIT WITH PD 8D AND MPAC= B  REVS B0
		PUSH	COS		# PD 10D
		STODL	COB		# PD 8D    COS(B) B-1
		SIN			#          SIN(B) B-1
		STODL	SOB		#           SETUP INPUT FOR NEWANGLE
			FSUBO		#                     8-9D=FSUBO
		PDDL	PUSH		# PD 10D THEN 12D   10-11D=FDOT
			FDOT
		AXT,1	CALL		# F REQUIRES SL 1, SL 6 IN NEWANGLE
			4
			NEWANGLE	# EXIT WITH PD 8D AND MPAC= F REVS B0
		STODL	AVECTR +2	# SAVE F TEMP
			NODIO		#                     8-9D=NODIO
		PDDL	PUSH		# PD 10D THEN 12D   10-11D=NODDOT
			NODDOT		#                     MPAC=T
		AXT,1	CALL		# NODE REQUIRES SL 0, SL 5 IN NEWANGLE
			5
			NEWANGLE	# EXIT WITH PD 8D AND MPAC= NODI REVS B0
## Page 1214
		PUSH	COS		# PD 10D   8-9D= NODI  REVS  B0
		PUSH			# PD 12D 10-11D= COS(NODI)  B-1
		STORE	AVECTR
		DMP	SL1R
			COB		#                         COS(NODI)    B-1
		STODL	BVECTR +2	# PD 10D   20-25D=AVECTR= COB*SIN(NODI)
		DMP	SL1R		#                         SOB*SIN(NODI)
			SOB
		STODL	BVECTR +4	# PD 8D
		SIN	PUSH		# PD 10D                  -SIN(NODI)   B-1
		DCOMP			#          26-31D=BVECTR= COB*COS(NODI)
		STODL	BVECTR		# PD 8D                   SOB*COS(NODI)
			AVECTR +2	# MOVE F FROM TEMP LOC. TO 504F
		STODL	504F
		DMP	SL1R
			COB
		STODL	AVECTR +2
			SINNODI		# 8-9D=SIN(NODI)  B-1
		DMP	SL1R
			SOB
		STODL	AVECTR +4	#                          0
			HI6ZEROS	#         8-13D= CVECTR= -SOB  B-1
		PDDL	DCOMP		# PD 10D                  COB
			SOB
		PDDL	PDVL		# PD 12D THEN PD 14D
			COB
			BVECTR
		VXSC	PDVL		# PD 20D         BVECTR*SINI  B-2
			SINI
			CVECTR
		VXSC	VAD		# PD 14D         CVECTR*COSI  B-2
			COSI
		VSL1
		STOVL	MMATRIX +12D	# PD 8D  M2=BVECTR*SINI+CVECTR*COSI  B-1
		VXSC	PDVL		# PD 14D
			SINI		#                CVECTR*SINI  B-2
			BVECTR
		VXSC	VSU		# PD 8D          BVECTR*COSI  B-2
			COSI
		VSL1	PDDL		# PD 14D
			504F		# 8-13D=DVECTR=BVECTR*COSI-CVECTR*SINI B-1
		COS	VXSC
			DVECTR
		PDDL	SIN		# PD 20D  14-19D= DVECTR*COSF  B-2
			504F
		VXSC	VSU		# PD 14D          AVECTR*SINF  B-2
			AVECTR
		VSL1
		STODL	MMATRIX +6	# M1= AVECTR*SINF-DVECTR*COSF  B-1
			504F
## Page 1215
		SIN	VXSC		# PD 8D
		PDDL	COS		# PD 14D  8-13D=DVECTR*SINF B-2
			504F
		VXSC	VAD		# PD 8D         AVECTR*COSF B-2
			AVECTR
		VSL1	VCOMP
		STCALL	MMATRIX		# M0= -(AVECTR*COSF+DVECTR*SINF)  B-1
			EARTHMXX
# COMPUTE X=X0+(XDOT)(T+T0)
# 8-9D= XO (REVS B-0),PUSHLOC SET AT 12D
# 10-11D=XDOT (REVS/CSEC) SCALED B+23 FOR WEARTH,B+28 FOR NODDOT AND BDOT
#                         AND B+27 FOR FDOT
#  X1=DIFFERENCE IN 23 AND SCALING OF XDOT,=0 FOR WEARTH,5 FOR NODDOT AND
#                                          BDOT AND 4 FOR FDOT
# 6-7D=T (CSEC B-28), TIMSUBO= (CSEC B-42 TRIPLE PREC.)

NEWANGLE	DLOAD	SR		# ENTER PD 12D
			6D
			14D
		TAD	TLOAD		# CHANGE MODE TO TP
			TIMSUBO
			MPAC
		STODL	TIMSUBM		# T+T0 CSEC B-42
			TIMSUBM +1
		DMP			# PD 10D  MULT BY XDOT IN 10-11D
		SL*	DAD		# PD 8D   ADD XO IN 8-9D AFTER SHIFTING
			5,1		#         SUCH THAT SCALING IS B-0
		PUSH	SLOAD		# PD 10D SAVE PARTIAL (X0+XDOT*T) IN 8-9D
			TIMSUBM
		SL	DMP
			9D
			10D		# XDOT
		SL*	DAD		# PD 8D   SHIFT SUCH THAT THIS PART OF X
			10D,1		#         IS SCALED REVS/CSEC B-0
		BOV			# TURN OFF OVERFLOW IF SET BY SHIFT
			+1		# INSTRUCTION BEFORE EXITING
		RVQ			# MPAC=X= X0+(XDOT)(T+T0)  REVS B0

## Page 1216
# ..... EARTHMX SUBROUTINE .....
# SUBROUTINE TO COMPUTE THE TRANSFORMATION MATRIX M FOR THE EARTH

# CALLING SEQUENCE
#  L       CALL
#  L+1            EARTHMX

# SUBROUTINES USED
#  NEWANGLE

# INPUT
#    INPUT AVAILABLE FROM LAUNCH DATA     AZO  REVS B-0
#                                         TEPHEM  CSEC B-42
#  6-7D= TIME CSEC B-28

# OUTPUT
#  MMATRIX= 3X3 M MATRIX B-1   (STORED IN VAC AREA)

EARTHMX		STQ	SETPD		# SET   8-9D=AZO
			EARTHMXX
			8D		# 10-11D=WEARTH
		AXT,1			# FOR SL 5, AND SL 10  IN NEWANGLE
			0
		DLOAD	PDDL		#   LEAVING PD SET AT 12D FOR NEWANGLE
			AZO
			WEARTH
		PUSH	CALL
			NEWANGLE
		SETPD	PUSH		# 18-19D=504AZ
			18D		#                    COS(AZ) SIN(AZ) 0
		COS	PDDL		# 20-37D=  MMATRIX= -SIN(AZ) COS(AZ) 0 B-1
			504AZ		#                     0       0      1
		SIN	PDDL
			HI6ZEROS
		PDDL	SIN
			504AZ
		DCOMP	PDDL
			504AZ
		COS	PDVL
			HI6ZEROS
		PDDL	PUSH
			HIDPHALF
		GOTO
			EARTHMXX

## Page 1217
# ..... EARTHL SUBROUTINE .....
# SUBROUTINE TO COMPUTE L VECTOR FOR EARTH

# CALLING SEQUENCE
#  L       CALL
#  L+1            EARTHL

# INPUT
#  AXO,AYO SET AT LAUNCH TIME WITH AYO IMMEDIATELY FOLLOWING AXO IN CORE

# OUTPUT
#           -AX
#   MPAC=   -AY    RADIANS B-0
#             0

EARTHL		DLOAD	DCOMP
			AXO
		STODL	504LPL
			-AYO
		STODL	504LPL +2
			HI6ZEROS
		STOVL	504LPL +4
			504LPL
		RVQ

## Page 1218
# CONSTANTS AND ERASABLE ASSIGNMENTS
1B1		=	DP1/2		# 1 SCALED B-1
COSI		2DEC	.99964115 B-1	# COS(1 DEG 32.1 MIN) B-1
SINI		2DEC	.02678760 B-1	# SIN(1 DEG 32.1 MIN) B-1
RPREXIT		=	S1		# R-TO-RP AND RP-TO-R SUBR EXIT
EARTHMXX	=	S2		# EARTHMX,MOONMX SUBR. EXITS
504RPR		=	0D		# 6 REGS  R OR RP VECTOR
SINNODI		=	8D		# 2       SIN(NODI)
DVECTR		=	8D		# 6       D VECTOR MOON
CVECTR		=	8D		# 6       C VECTR MOON
504AZ		=	18D		# 2      AZ
TIMSUBM		=	14D		# 3       TIME SUB M (MOON) T+T0 IN GETAZ
504LPL		=	14D		# 6       L OR LP VECTOR
AVECTR		=	20D		# 6       A VECTOR (MOON)
BVECTR		=	26D		# 6       B VECTOR (MOON)
MMATRIX		=	20D		# 18      M MATRIX
COB		=	32D		# 2       COS(B) B-1
SOB		=	34D		# 2       SIN(B) B-1
504F		=	6D		# 2       F(MOON)
NODDOT		2DEC	-.457335143 E-2	# REVS/CSEC B+28=-1.07047016 E-6  RAD/SEC
FDOT		2DEC	.570862491	# REVS/CSEC B+27= 2.67240019 E-6  RAD/SEC
BDOT		2DEC	-3.07500412 E-8	# REVS/CSEC B+28=-7.19756666 E-14 RAD/SEC
NODIO		2DEC	-.960101269	# REVS B-0    = -6.03249419  RAD
FSUBO		2DEC	.415998375	# REVS B-0    =  2.61379488  RAD
BSUBO		2DEC	.0651205006	# REVS B=0    =  0.409164173 RAD
WEARTH		2DEC	.973561855	# REVS/CSEC B+23=7.29211515 E-5 RAD/SEC