Talk:Roman numerals/Encode

From Rosetta Code

I for one like Roman numerals

'Nuff said.     -- Gerard Schildberger (talk) 13:17, 29 November 2019 (UTC)

enforcing a requirement

The Java example does not enforce the requirement that the parameter for the conversion function must be a positive integer. Enforcement of such a requirement should result in an error condition, such as an exception, rather than simply no output when a value less than 1 is passed to the function.--Waldorf 21:14, 31 March 2008 (MDT)

Fixed. --Mwn3d 21:22, 31 March 2008 (MDT)
No, the requirement said to take a positive integer ..., it did NOT say that it HAD to be a positive integer. My REXX version also allows a non-positive number. I (and I assume others) have removed the error checking (such as negative numbers), non-whole numbers, and the like). I often remove a lot of error checking from my REXX code that I post as it would just clutter up the example with many, many error checks.


I'm pretty sure CD is 400. If you look at wp:Roman_numerals#Modern_Roman_numerals it shows it. --Mwn3d 21:20, 31 March 2008 (MDT)


Roman numerals are by no means standardized. You should reference the particular brand of encoding you wish to support. --IanOsgood 08:53, 1 April 2008 (MDT)

What are our choices? --Mwn3d 09:09, 1 April 2008 (MDT)
Project Euler had a similar task, where they addressed possible rules in a FAQ. Wikipedia has also a section on special rules. I guess the safe way is the way all examples so far do it. But maybe specifying it isn't important (I don't know which similarities/dissimilarities between different languages this task should highlight). --Dirkt 15:38, 1 April 2008 (MDT)

Some options are:

  • user of lowercase Roman numerals (letters)
  • use of (Roman) fractions [based on twelfths]
  • expression of large numbers
  • support for   zero   (or nothing)
  • Attic style
  • old style
  • modern style

Attic style is a Greek style (also known as acrophonic or Herodianic numerals). Attic numerals were in use by the Greeks around the 7th century BCE before they converted to their later Greek numerals, but you can clearly see the influence they had on Roman numerals.

Modern style is where   IV   is always used instead of   IIII,   but almost all clock-face makers (of clocks and wrist watches that use Roman numerals) today use the old style.

Also where   u   is used in addition to (or instead of)  v,     and   j   is used in in place of (any) trailing   i.

The manner of expressing large numbers could be considered an option.   The REXX program that I included uses parentheses and deep parentheses for large numbers.

There are also post-modern (my word, I don't know the real word for this style) where many other (Latin) letters are used for   200,   400,   and other numbers. -- Gerard Schildberger 07:47, 14 July 2012 (UTC)

Perl problem

The use of the works_with template is interacting badly with the semantic wiki markup, but I'm not sure how to unpick the mess so I'll just flag this up for now. –Donal Fellows 08:46, 30 July 2010 (UTC)

Yeah, I've been wanting to poke the SMW folks in #semantic-mediawiki for thoughts (you can see other weird issues in Special:Properties, but I haven't had time. --Michael Mol 12:15, 30 July 2010 (UTC)

Parsing roman numerals

Is there a page for that? I couldn't find one...

I'm not aware of one. It seems a perfectly appropriate task idea. Why don't you create it? (I'd suggest you create an account first) --Michael Mol 20:03, 9 May 2011 (UTC)
If you do create it I would suggest putting it at Roman numberals/Decode or something like that. Also check for task creation hints at Rosetta Code:Add a Task. --Mwn3d 20:27, 9 May 2011 (UTC)
I've done this (minus the typo): Roman numerals/Decode --Mikachu 20:48, 9 May 2011 (UTC)
Heh...good catch. Anyway it looks good. I'll move this task to Roman numerals/Encode so it's consistent. --Mwn3d 21:11, 9 May 2011 (UTC)

Additional Roman numerals: Ⅰ, Ⅴ, Ⅹ, Ⅼ, Ⅽ, Ⅾ, Ⅿ, ⅰ, ⅴ, ⅹ, ⅼ, ⅽ, ⅾ, ⅿ, ↀ, ↁ, ↂ, Ↄ

It might be worth permitting full range of Roman numerals eg:

  • Ⅰ, Ⅴ, Ⅹ, Ⅼ, Ⅽ, Ⅾ, Ⅿ, ⅰ, ⅴ, ⅹ, ⅼ, ⅽ, ⅾ, ⅿ, ↀ, ↁ, ↂ, Ↄ

c.f. wiktionary

NevilleDNZ 23:16, 30 November 2011 (UTC)

Is it just me or can anyone else see those characters? All I see (under Microsoft Internet Explorer and FireFox Aurora) are "empty squares". Gerard Schildberger
I see the characters in FF 12. --Mwn3d 02:57, 26 April 2012 (UTC)
It depends on the fonts you've got installed; if they don't have the character glyph, you get that box (on Windows; different platforms have different substitutions). Not much we can do about that. –Donal Fellows 10:46, 26 April 2012 (UTC)
I think they're permitted. Worth it? I dunno. Judging by the "modern Roman numerals" stuff I don't think people really use them anymore. If you want to then go for it. --Mwn3d 02:57, 26 April 2012 (UTC)

UNIX Shell problem (fixed)

There is an error in how the function for encoding Arabic to Roman numbers is currently written for the UNIX Shell. In fact, the number "9" is misencoded in "VIV" instead of "IX", as also clear from the published example: 1999 = MCMXCVIV . This error is easily fixable by inserting the "9" in the values array: change the line

   local values=( 1000 900 500 400 100 90 50 40 10 5 4 1 )


   local values=( 1000 900 500 400 100 90 50 40 10 9 5 4 1 )