These Casio calculators always made me wonder. When their designers gave them a whopping memory capacity of 29 program steps, exactly what kind of programs did they have in mind? When they decided to implement two conditional functions, [X>0] and [X<=M], both of which cause program execution to resume at the first program step, what kind of algorithms did they envision? These programming features make an otherwise pleasant scientific calculator singularly frustrating when one tries to put them to their intended use: that is, when one tries to use their programming capability to implement simple scientific or technical programs.

That said, it is actually possible to squeeze moderately complex algorithms into those 29 program steps. This is due, at least in part, to the fact that this family of Casio machines all offer a fully merged programming model: multikey instructions such as [SHIFT] [Min], or [Kin] [+] [1] all occupy a single location in program memory.

The following program neatly demonstrates this by implementing the logarithm of the Gamma function using Stirling's formula and a simple iteration to improve the accurace for small values. As a result, the program computes the Gamma function with six-digit accuracy for all positive arguments. That is a pretty decent result for a mere 29 program steps!

K3: 1/12 (0.0833333333333)
K4: 2×π  (6.2831853072)

+
ln
Kin+ 1
9
Min
1
=
x<=M
×
Kin 2
ln
-
Kout 2
+
Kout 4
÷
Kout 2
÷
ln
x-y
2
+
Kout 3
÷
Kout 2
-
0
x-K 1
=