HP-42S (Free42, DM-42) mini-challenge – Wallis Product

[Gerson W. Barbosa]

Back on topic, I've received two solutions from former forum member Mike (Stgt). J-M Baillard's and Werner's solution, which I assume to be exactly the same, are unbeatable. Please consider these as hors-concours submissions. The first Mike's solution is one byte less, but one step longer, hence his attempt to overcome that limitation by producing his own plug-in ROM (user-code only) with some more trig funcions, which I haven't tested yet. Again, please don't take that as some kind of lack of sportmanship (Mike used the German Fußball term "Nachtreten"), rather as another valuable contribution to this interesting topic.

Code:

 
00 { 22-Byte Prgm }
01▸LBL "WP"
02 2
03▸LBL 01
04 RCL ST Y
05 STO+ ST X
06 1/X
07 ASIN
08 COS
09 X↑2
10 ÷
11 DSE ST Y
12 GTO 01
13 END

(24 bytes on the HP-41)

Plug-in ROM HP-41 version, 12-step, 24 bytes:

Code:


01▶LBL "WP"
02 2
03▶LBL 01
04 RCL Y
05 ST+ X
06 XROM "ACSC"
07 COS
08 X^2
09 /
10 DSE Y
11 GTO 01
12 END

"ACSC" atands for arccosecant, the inverse cosecant function.