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Re: Roman Numerals

• To: mathgroup at smc.vnet.net
• Subject: [mg73717] Re: Roman Numerals
• From: "janos" <janostothmeister at gmail.com>
• Date: Sun, 25 Feb 2007 04:40:40 -0500 (EST)
• References: <erjo00$nmc$1@smc.vnet.net><ermep7$inb$1@smc.vnet.net>

On Feb 23, 11:13 am, "dimitris" <dimmec... at yahoo.com> wrote:
> Dear Ajit
>
> I think you will see many interesting things downloading the package
> and the notebook
> AntiqueNotations of Robby Villegas from here
>
> http://library.wolfram.com/infocenter/Demos/4952/
>
> Regards
> Dimitris
>
> =CF/=C7 Mr Ajit Sen =DD=E3=F1=E1=F8=E5:
>
> > Dear Mathgroup,
>
> >   Does Mathematica have any function to convert Arabic
> >   numerals to Roman, & vice versa? I'm thinking of
> >   something like
>
> >    Roman[2007]  ---> MMVII
>
> >    Arabic[MDCCLXIV] ---> 1764
>
> >   I just thought about that after seeing the date in
> >        the  credits of an old movie, & I reckoned it'd
> > be faster to use Mathematica than use a convertor on the Web.
>
> > I could not get any info from the Help browser or the archive.
> > A Yes/No  answer with a few words will do.  I don't
> > really need a code. Unless someone has plenty of spare
> > time.
>
> >    Thanks.
> >   Ajit Sen.
>
> > ___________________________________________________________
> > Now you can scan emails quickly with a reading pane. Get the new Yahoo! M
>
> ail.http://uk.docs.yahoo.com/nowyoucan.html
Dear Ajit,

I also liked the proposed nb,
but you might be still be interested in reading
this small recursive program calculating
Roman numerals (form our book with L. Szili, 1996).

arabic = Union[10^Range[0, 3], Flatten[Outer[Times, {9, 5,4},
10^Range[0, 2]]], {0}];
roman = ToString /@ {{}, I, IV,V, IX, X, XL, L, XC, C, CD, D, CM, M};
MapThread[SetDelayed, {ToRoman /@ arabic, roman}];
cap[x_Integer /; 0 < x < 4000] := First[Select[Reverse[arabic], # < x
&, 1]];
ToRoman[x_Integer /; 0 < x < 4000] := SequenceForm[ToRoman[cap[x]],
ToRoman[x - cap[x]]]

ToRoman /@ (2^Range[0, 12])