THE 'ARCCOS' FUNCTION
(Offset 23: 'acs')

This subroutine handles the function ACS X and returns a real number from zero to PI
inclusive which is equal to the value in radians of the angle whose cosine is X.
	This subroutine uses the relation:
		ACS X = PI/2 - ASN X

3843	acs	RST	0028,FP-CALC	X
		DEFB	+22,asn	ASN X
		DEFB	+A3,stk-pi/2	ASN X,PI/2
		DEFN	+03,subtract	ASN X-PI/2
		DEFB	+1B,negate	PI/2-ASN X = ACS X
		DEFB	+38,end-calc
		RET		Finished: 'last value' = ACS X.

THE 'SQUARE ROOT' FUNCTION
(Offset 28: 'sqr')

This subroutine handles the function SQR X and returns the positive square root of the
real number X if X is positive, and zero if X is zero. A negative value of X gives rise to
report A - invalid argument (via In in the EXPONENTIATION subroutine).
	This subroutine treats the square root operation as being X**.5 and therefore stacks
the value .5 and proceeds directly into the EXPONENTIATION subroutine.

384A	sqr	RST	0028,FP-CALC	X
		DEFB 	+31,duplicate 	X,X
		DEFB 	+30,not 	X,(1/0)
		DEFB 	+00,jump-true 	X
		DEFB 	+1E,to 386C,LAST	X

The jump is made if X = 0, otherwise continue with:

		DEFB 	+A2,stk-half 	X,.5
		DEFB 	+38,end-calc

and then find the result of X**.5.

THE 'EXPONENTIATION' OPERATION
(Offset 06: 'to-power')

This subroutine performs the binary operation of raising the first number, X, to the
power of the second number, Y.
	The subroutine treats the result X**Y as being equivalent to EXP (Y*LN X). It
returns this value unless X is zero, in which case it returns 1 if Y is also zero (0**0=1),
returns zero if Y is positive and reports arithmetic overflow if Y is negative.

3851 	to-power 	RST 	0028,FP-CALC 	X,Y
		DEFB 	+01,exchange 	Y,X
		DEFB 	+31,duplicate 	Y,X,X
		DEFB 	+30,not 	Y,X,(1/0)
		DEFB 	+00,jump-true 	Y,X
		DEFB 	+07,to 385D,XIS0 	Y,X

The jump is made if X = 0, otherwise EXP (Y*LN X) is formed.

		DEFB 	+25,ln 	Y,LN X
		
Giving report A if X is negative.

		DEFB 	+04,multiply 	Y*LN X
		DEFB 	+38,end-calc
		JP 	36C4,EXP 	Exit via EXP to form EXP
				(Y*LN X).

The value of X is zero so consider the three possible cases involved.

385D 	XIS0 	DEFB 	+02,delete 	Y
		DEFB 	+31,duplicate 	Y,Y
		DEFB 	+30,not 	Y,(1/0)
		DEFB 	+00,jump-true 	Y