Report 6 - Number too big

3703	REPORT-6	RST	0008,ERROR-1	Call the error handling
		DEFB	+05	routine.

3705	N-NEGTV	JR	C,370E,RSLT-ZERO	The result is to be zero if N is
				less than -255 decimal.
		SUB	(HL)	Subtract ABS N from the
				exponent as N was negative.
		JR	NC,370E,RSLT-ZERO	Zero result if e less than zero.
		NEG		Minus e is changed to e.
370C	RESULT-OK	LD	(HL),A	The exponent, e, is entered.
		RET		
370E	RESULT-ZERO	RST	0028,FP-CALC	Use the calculator to make the
		DEFB	+02,delete	'last value' zero.
		DEFB	+A0,stk-zero	
		DEFB	+38,end-calc	
		RET		Finished, with EXP X = 0.

THE 'NATURAL LOGARITHM' FUNCTION
(Offset 25: 'ln')

This subroutine handles the function LN X and is the second of the four routines that use SERIES GENERATOR to produce Chebyshev polynomials.
The approximation to LN X is found as follows:

i. X is tested and report A is given if X is not positive.

ii. X is then split into its true exponent, e', and its mantissa X' = X/(2**e'), where X' is greater than, or equal to, 0.5 but still less than 1.

iii. The required value Y1 or Y2 is formed. If X' is greater than 0.8 then Y1=e'*LN 2 and if otherwise Y2 = (e'-1)*LN 2.

iv. If X' is greater than 0.8 then the quantity X'-1 is stacked; otherwise 2*X'-1 is stacked.

v. Now the argument Z is formed, being if X' is greater than 0.8, Z = 2.5*X'-3; otherwise Z = 5*X'-3. In each case, -1 <=Z <=1, as required for the series to converge.

vi. The SERIES GENERATOR is used to produce the required function.

vii. Finally a simply multiplication and addition leads to LN X being returned as the 'last value'.

3713	ln	RST	0028,FP-CALC	X

Perform step i.

		DEFB	+3D,re-stack	X (in full floating-point form)
		DEFB	+31,duplicate	X, X
		DEFB	+37,greater-0	X, (1/0)
		DEFB	+00,jump-true	X
		DEFB	+04,to 371C, VALID	X
		DEFB	+38,end-calc	X

Report A - Invalid argument

371A	REPORT-A	RST	0008,ERROR-1	Call the error handling
		DEFB	+09	routine.

Perform step ii.

371C	VALID	DEFB	+A0,stk-zero	X,0	The deleted 1 is
		DEFB	+02,delete	X	overwritten with zero.
		DEFB	+38,end-calc	X
		LD	A,(HL)	The exponent, e, goes into A.
		LD	(HL),+80	X is reduced to X'.
		CALL	2D28,STACK-A	The stack holds: X', e.
		RST	0028,FP-CALC	X', e
		DEFB	+34,stk-data	X', e, 128 (decimal)
		DEFB	+38,exponent+88