[pdp8.git] / sw / f4 / FRTSRC / cosh.ra

/
/ VERSION 5A 4-27-77  PT
/
/	C  O  S  H
/	-  -  -  -
/
/SUBROUTINE	COSH(X)
/
/ VERSION 5A 4-27-77  PT
	SECT	COSH
	JA	#COSH
COSHE,	FLDA	COSHB		/GIVE INFINITY IN CASE OF NO REC
	EXTERN	#ARGER
	TRAP4	#ARGER
	TEXT	+COSH  +
COSHXR,	SETX	XRCOSH
	SETB	BPCOSH
BPCOSH,	FNOP
	0
	0
XRCOSH,	F 0.0
COSH7,	F 0.0
COSH8,	F 0.0
F1COSH,	F 1.
F2COSH,	F 2.
	ORG	10*3+BPCOSH
	FNOP
	JA	COSHXR
	0
CSHRTN,	JA	.
/
COSHLG,	0
	2613
	4412
/
COSHB,	3777
	3777
	7777
/
/
COSH1,	F 88.029			/LIMIT FACTOR.
	BASE	0
#COSH,	STARTD
	FLDA	10*3
	FSTA	CSHRTN
	FLDA	0
	SETX	XRCOSH
	SETB	BPCOSH
	BASE	BPCOSH
	LDX	1,1
	FSTA	BPCOSH
	FLDA%	BPCOSH,1	/ADDR OF X
	FSTA	BPCOSH
	STARTF
	FLDA%	BPCOSH	/GET X
	FSTA	COSH8		/SAVE ARGUMENT
	JGE	.+3		/ABS(X)
	FNEG
	FSTA	COSH7
	FSUB	COSH1		/TEST FOR LIMITS.
	JGE	COSHBG
	EXTERN	EXP
	JSR	EXP		/EXP(X)
	JA	.+4
	JA	COSH8
	FSTA	COSH7
	FLDA	F1COSH		/1.
	FDIV	COSH7		/ 1./EXP(X)
	FADD	COSH7		/ EXP(X)+1./EXP(X)
	FDIV	F2COSH		/ (EXP(X)+1./EXP(X))2.
	JA	CSHRTN		/AND THAT IS THE DEFINITION OF COSH.
/
/
COSHBG,	FSUB	COSHLG		/SEE IF TOO BIG
	JGT	COSHE		/YEP. ERROR
	FADD	COSH1		/READD IN SUBTRACTION FACTOR.
	FSTA	COSH8		/ EXP(ABS(X)-LN(2))
	EXTERN	EXP
	JSR	EXP
	JA	.+4
	JA	COSH8
	JA	CSHRTN		/ A VERY GOOD APPROXIMATION.
\f
Commit	Line	Data
	1	/
	2	/ VERSION 5A 4-27-77 PT
	3	/
	4	/ C O S H
	5	/ - - - -
	6	/
	7	/SUBROUTINE COSH(X)
	8	/
	9	/ VERSION 5A 4-27-77 PT
	10	SECT COSH
	11	JA #COSH
	12	COSHE, FLDA COSHB /GIVE INFINITY IN CASE OF NO REC
	13	EXTERN #ARGER
	14	TRAP4 #ARGER
	15	TEXT +COSH +
	16	COSHXR, SETX XRCOSH
	17	SETB BPCOSH
	18	BPCOSH, FNOP
	19	0
	20	0
	21	XRCOSH, F 0.0
	22	COSH7, F 0.0
	23	COSH8, F 0.0
	24	F1COSH, F 1.
	25	F2COSH, F 2.
	26	ORG 10*3+BPCOSH
	27	FNOP
	28	JA COSHXR
	29	0
	30	CSHRTN, JA .
	31	/
	32	COSHLG, 0
	33	2613
	34	4412
	35	/
	36	COSHB, 3777
	37	3777
	38	7777
	39	/
	40	/
	41	COSH1, F 88.029 /LIMIT FACTOR.
	42	BASE 0
	43	#COSH, STARTD
	44	FLDA 10*3
	45	FSTA CSHRTN
	46	FLDA 0
	47	SETX XRCOSH
	48	SETB BPCOSH
	49	BASE BPCOSH
	50	LDX 1,1
	51	FSTA BPCOSH
	52	FLDA% BPCOSH,1 /ADDR OF X
	53	FSTA BPCOSH
	54	STARTF
	55	FLDA% BPCOSH /GET X
	56	FSTA COSH8 /SAVE ARGUMENT
	57	JGE .+3 /ABS(X)
	58	FNEG
	59	FSTA COSH7
	60	FSUB COSH1 /TEST FOR LIMITS.
	61	JGE COSHBG
	62	EXTERN EXP
	63	JSR EXP /EXP(X)
	64	JA .+4
	65	JA COSH8
	66	FSTA COSH7
	67	FLDA F1COSH /1.
	68	FDIV COSH7 / 1./EXP(X)
	69	FADD COSH7 / EXP(X)+1./EXP(X)
	70	FDIV F2COSH / (EXP(X)+1./EXP(X))2.
	71	JA CSHRTN /AND THAT IS THE DEFINITION OF COSH.
	72	/
	73	/
	74	COSHBG, FSUB COSHLG /SEE IF TOO BIG
	75	JGT COSHE /YEP. ERROR
	76	FADD COSH1 /READD IN SUBTRACTION FACTOR.
	77	FSTA COSH8 / EXP(ABS(X)-LN(2))
	78	EXTERN EXP
	79	JSR EXP
	80	JA .+4
	81	JA COSH8
	82	JA CSHRTN / A VERY GOOD APPROXIMATION.
	83	\f