A large commit.

[pdp8.git] / sw / os8 / v3d / sources / fortran / dectapes / dectape2 / dlog.ra

/
/
/	D L O G
/	- - - -
/
/ VERSION 5A 4-27-77  PT
/
/LOGE(X)
/
/X=2^N*F
/
/LOGE(X)
 /= N*LOGE(2)+LOGE(F)
/
/
	SECT	DLOG
	JA	#DALOG
	DPCHK
/
/IF X<=0 - IT IS AN ERROR
	EXTERN	#ARGER
DALERR,	TRAP4	#ARGER
/
	TEXT	+DLOG  +
DALXR,	SETX	XRDAL
	SETB	BPDAL
BPDAL,	F 0.0
XRDAL,	F 0.0
	F 0.0
	ORG 10*3+BPDAL
	FNOP
	JA	DALXR
	0
DALRTN,	JA	.
N,	F 0.0
	F 0.0
F,	F 0.0
	F 0.0
DAL1,	F 1.0
	F 0.0
/
DT7,	7776		/1/7
	2222
	2222
	2222
	2222
	2221
DT6,	7776		/-1/6
	5252
	5252
	5252
	5252
	5252
DT5,	7776		/1/5
	3146
	3146
	3146
	3146
	3146
DT4,	7776		/-1/4
	4000
	0
	0
	0
	0
DT3,	7777		/1/3
	2525
	2525
	2525
	2525
	2524
DT2,	7777		/-1/2
	4000
	0
	0
	0
	0
/
A0,	F 1.84375
	F 0.0
A1,	F 1.65625
	F 0.0
A2,	F 1.500
	F 0.0
A3,	F 1.375
	F 0.0
A4,	F 1.250
	F 0.0
A5,	F 1.1875
	F 0.0
A6,	F 1.09375
	F 0.0
A7,	F 1.03125
	F 0.0
LA0,	0		/.6118015411059928976
	2344
	7603
	2325
	4250
	3144
LA1,	0		/.5045560107523952859
	2011
	2512
	4551
	3503
	7657
LA2,	7777		/.4054651081081643810
	3174
	6217
	5457
	7141
	1370
LA3,	7777		/.3184537311185346147
	2430
	3057
	0207
	0573
	0232
LA4,	7776		/.2231435513142097553
	3443
	7737
	0746
	5150
	4146
LA5,	7776		/.1718502569266592214
	2577
	6301
	6051
	7117
	2356
LA6,	7775		/.08961215868968712374
	2674
	1512
	1271
	2655
	1272
LA7,	7773		/.030771658666753687
	3740
	5154
	1636
	0313
	7764
D16,	F 16.0
	F 0.0
D8,	F 8.0
	F 0.0
CUM,	F 0.0
	F 0.0
DLOGE2,	0
	2613
	4413
	7676
	4347
	5715
/
/PICK UP X
	BASE	0
#DALOG,	STARTD
	FLDA	10*3
	FSTA	DALRTN
	FLDA	0
	SETX	XRDAL
	SETB	BPDAL
	BASE	BPDAL
	LDX	1,1
	FSTA	BPDAL
	FLDA%	BPDAL,1		/ADDRESS
	FSTA	BPDAL
	STARTE
	FLDA%	BPDAL		/AND X
	JLE	DALERR		/X <= 0 IS ERROR
	FSUB	DAL1		/SUB 1.0
	JNE	DALA
	FCLA			/LOG(1)=0
	JA	DALRTN
/
DALA,	FADD	DAL1		/ADD BACK
	FSTA	XRDAL		/STORE AT X
/EXPONENT STORED IN XR0
/MANTISSA STORED IN XR1-5
/PICK UP EXP + MULTIPLY BY LOGE(2)
/
	XTA	0
	FMUL	DLOGE2
	FSTA	N		/N*LOGE(2)
/XRDAL IS NOW FRACTION IN RANGE .5<=F<1.0
/COMPUTE LOG(F) BY
/LOG(F)=LOG(A(K1)*A(K2)...(F))-(LOG(A(K1))+
/	LOG(A(K2))...)
/FIT F IN A 1/16 RANGE
/I.E. 1/2-9/16,9/16-10/16,ETC.
/MULTIPLY F BY APPROPRIATE A(K) MULTIPLIER
/KEEP RUNNING SUM OF LOG(A(K))
/CONTINUE UNTIL F>1

/
	LDX	0,0
	FLDA	XRDAL
	FSTA	F
	FCLA
	FSTA	CUM
DALB,	FLDA	F
	FMUL	D16	/16 REAL PARTS
	FSUB	D8		/NEED JUST 8
	ATX	1
	FLDA	A0,1		/GET MULTIPLIER
	FMULM	F
	FLDA	LA0,1		/ADD LOG(A(K)) TO SUM
	FADDM	CUM
	FLDA	F
	FSUB	DAL1
	JLT	DALB
/NOW F>1. USE TAYLOR SERIES
/LOG(T)=Z-(Z^2)/2+(Z^3)/3+...  WHERE Z=T-1
	FLDA	F
	FSUB	DAL1	/F-1.0
	FSTA	F
	FMUL	DT7
	FADD	DT6
	FMUL	F
	FADD	DT5
	FMUL	F
	FADD	DT4
	FMUL	F
	FADD	DT3
	FMUL	F
	FADD	DT2
	FMUL	F
	FADD	DAL1
	FMUL	F
	FSUB	CUM
	FADD	N
	JA	DALRTN
\f