HP 42S: Programming Complexity Question
01-25-2016, 05:26 PM
Post: #1
 Gerald H Senior Member Posts: 1,573 Joined: May 2014
HP 42S: Programming Complexity Question
Is it really more difficult to convert Arabic numbers to Roman than Roman to Arabic?

Here a 42S programme for A2R

size is 162 Bytes & here for R2A

size 78 Bytes.

Is it my poor programming or is the inverse problem really so much more difficult?
01-25-2016, 11:03 PM
Post: #2
 TASP Senior Member Posts: 401 Joined: Mar 2015
RE: HP 42S: Programming Complexity Question
"Back in the day" it was noted the longer calendar printing programs (HP41 series) tended to print calendars faster then the shorter programs.

I've tried to not let anything about programming amaze me since.

2speed HP41CX,int2XMEM+ZEN, HPIL+DEVEL, HPIL+X/IO, I/R, 82143, 82163, 82162 -25,35,45,55,65,67,70,80
01-26-2016, 07:25 AM
Post: #3
 emece67 Senior Member Posts: 379 Joined: Feb 2015
RE: HP 42S: Programming Complexity Question
(01-25-2016 08:01 PM)Mike (Stgt) Wrote:  Example: compare the Euclidian algorithm on an AOS system vs one on a UPN machine.

Excuse my ignorance but, what are AOS systems & UPN machines?
01-26-2016, 07:37 AM
Post: #4
 walter b On Vacation Posts: 1,957 Joined: Dec 2013
RE: HP 42S: Programming Complexity Question
(01-26-2016 07:25 AM)emece67 Wrote:  ... what are AOS systems & UPN machines?

AOS = Algebraic Operating System
UPN = RPN in German

d:-)
01-26-2016, 12:15 PM (This post was last modified: 09-29-2016 08:57 AM by renif.)
Post: #5
 renif Junior Member Posts: 33 Joined: Jun 2014
RE: HP 42S: Programming Complexity Question
"Is it really more difficult to convert Arabic numbers to Roman than Roman to Arabic?"

Well, that definitely is a question relating to the mathematical structure of the problem. IMHO the size comparison between the two codes for the HP-42s at least gives a hint. It seems to be similar on other machines and in other languages, but this difference becomes especially apparent with implementations in an environment with very restricted memory, where the conversion Roman to Arabic can be realized, but not the opposite. In my old collection of programs, e.g. I found one for the TI-57 (max. 50 program steps) converting from Roman to Arabic (or better: Hindu numeral system). Never saw a program for the TI-57 converting from Hindu to Roman numerals. But that's only another hint, not a real proof, that the one algorithm is more difficult than the other.
01-26-2016, 01:42 PM
Post: #6
 Gerald H Senior Member Posts: 1,573 Joined: May 2014
RE: HP 42S: Programming Complexity Question
Here a smaller A2R programme which produces valid Roman numerals BUT only produces forms such as MIIII for 1004 & not MIV:

Code:
 00 { 101-Byte Prgm } 01>LBL "A2R" 02 CLA 03 1.007 04 RCL ST Y 05>LBL 00 06>LBL 14 07 XEQ IND ST Y 08 X>Y? 09 GTO 15 10 - 11 GTO 14 12>LBL 15 13 Rv 14 ISG ST Y 15 GTO 00 16 RCL ST Z 17 AVIEW 18 RTN 19>LBL 01 20 1E3 21 X<=Y? 22 |-"M" 23 RTN 24>LBL 02 25 500 26 X<=Y? 27 |-"D" 28 RTN 29>LBL 03 30 100 31 X<=Y? 32 |-"C" 33 RTN 34>LBL 04 35 50 36 X<=Y? 37 |-"L" 38 RTN 39>LBL 05 40 10 41 X<=Y? 42 |-"X" 43 RTN 44>LBL 06 45 5 46 X<=Y? 47 |-"V" 48 RTN 49>LBL 07 50 1 51 X<=Y? 52 |-"I" 53 .END.
01-26-2016, 04:28 PM
Post: #7
 emece67 Senior Member Posts: 379 Joined: Feb 2015
RE: HP 42S: Programming Complexity Question
(01-26-2016 07:37 AM)walter b Wrote:
(01-26-2016 07:25 AM)emece67 Wrote:  ... what are AOS systems & UPN machines?

AOS = Algebraic Operating System
UPN = RPN in German

d:-)

Thanks,
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