Roman Numeral in Mathematica

Published on 28 April 2022 (Updated: 02 February 2023)

Roman Numeral in Mathematica

Welcome to the Roman Numeral in Mathematica page! Here, you’ll find the source code for this program as well as a description of how the program works.

Current Solution

(* Code *)

(* The actual Roman numeral converter operating on Mathematica strings: *)

romanNumerals = s \[Function] Fold[
    (* conversion operating on pairs of subsequent values*)
    Function[{a, ii}, If[GreaterEqual @@ ii, a + First[ii], a - First[ii]]],
    0,
    Partition[(* pairs of subsequent values*)
     Append[ (* append zero so the last value still forms a pair *)
      ReplaceAll[Characters[s], (* convert to list of decimal values *)
       {"I" -> 1, "V" -> 5, "X" -> 10, "L" -> 50, "C" -> 100, "D" -> 500, "M" -> 1000}],
      0],
     2, 1]];

(* The outer function provides the 'user interface': *)

romanNumeralsMain = s \[Function]
   Catch[
    romanNumerals[
     If[
      StringQ[s] \[And] StringMatchQ[s, ("I" | "V" | "X" | "L" | "C" | "D" | "M") ...],
      s,
      Throw["Error: invalid string of roman numerals"]]]];


(* Valid Tests *)

Print /@ romanNumeralsMain /@ {
    "", "I", "V", "X", "L", "C", "D", "M", "XXV", "XIV"
    };


(* Invalid Tests *)

romanNumeralsMain["XT"]

Roman Numeral in Mathematica was written by:

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How to Implement the Solution

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How to Run the Solution

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