OK, so it's only 29 program steps in this calculator. Only seven memory registers. Apart from a conditional return-to-start capability, no other control transfer instructions. How utterly useless, right?

Wrong, as it was recently demonstrated by a few programs sent to me by a fellow calculator enthusiast, Herman van Elburg.

Herman's programs were actually written for the Casio fx-3600P (a close relative to the EC-4024, which itself is an OEM Casio machine) which has a slightly higher program capacity; but one of his programs uses only 25 program steps, so it fits nicely into the more limited program memory of the EC-4024.

What program? Well, my favorite programming example of course, the Gamma function. Or, in this case, the incomplete Gamma function which of course nicely approximates the "real" Gamma function if you choose a sufficiently high integration limit (Herman recommends x=2a+25). This is absolutely stunning; I never expected to be able to fit that algorithm into this calculator's limited program memory. Then again, until I received Herman's first e-mail, I didn't realize that this machine not only had four-function memory arithmetic on its six K-registers, but these memory arithmetic instructions were stored in memory in a fully merged form. Nice!

Herman's program is actually a set of two programs; the first one initializes variables, the second calculates the value of the incomplete Gamma function iteratively. For instance, if you wish to calculate the incomplete Gamma function of 5 with an integration limit of 35, you'd need the following keystrokes:

    35 P1 5 RUN P2

With most reasonable arguments, the function's value is calculated in about a minute or so.

P1-1		Kin 2		INV Kout 2		store x
P1-2		xy		INV ×
P1-3		ENT		RUN		enter a
P1-4		Kin 1		INV Kout 1
P1-5		÷
P1-6		Kout 2				recall (z+n)
P1-7		ex		INV ln
P1-8		=
P1-9		Kin 3
P2-1		1
P2-2		X<->K 1		INV x2 1
P2-3		Kin + 1		INV Kout + 1		First time, it's K3/a; second time K3×n/a(a+1)
P2-4		Kin ÷ 3		INV Kout ÷ 3
P2-5		Kout 3
P2-6		+
P2-7		Kout 2
P2-8		Kin × 3		INV Kout × 3
P2-9		Kout 4
P2-10		-
P2-11		X<->K 4		INV x2 4
P2-12		=
P2-13		x>0		INV [(---		Loop up if a not done
P2-14		+/-
P2-15		x>0		INV [(---
P2-16		X<->K 4