Module:Roman Explained

-- This module implements .requirestrict

local p =

-- This function implements the template.local function overline(s) return mw.ustring.format('

%s', s)end

-- Gets the Roman numerals for a given numeral table. Returns both the string of-- numerals and the value of the number after it is finished being processed.local function getLetters(num, t) local ret = for _, v in ipairs(t) do local val, letter = unpack(v) while num >= val do num = num - val table.insert(ret, letter) end end

return table.concat(ret), numend

-- The main control flow of the module.local function _main(args) -- Get input and exit displaying nothing if the input is empty. if args[1]

nil then return end local num = tonumber(args[1]) if not num or num < 0 or num

math.huge then error('Invalid number ' .. args[1], 2) elseif num

0 then return 'N' end

-- Return a message for numbers too big to be expressed in Roman numerals. if num >= 5000000 then return args[2] or 'N/A' end

local ret = -- Find the Roman numerals for the large part of numbers. -- 23 April 2016 - tweaked to >= 4000 to accept big Roman 'IV' -- The if statement is not strictly necessary, but makes the algorithm -- more efficient for smaller numbers. if num >= 4000 then local bigRomans = local bigLetters bigLetters, num = getLetters(num, bigRomans) ret = overline(bigLetters) end

-- Find the Roman numerals for numbers less than the big Roman threshold. local smallRomans = local smallLetters = getLetters(num, smallRomans) ret = ret .. smallLetters

if args.fraction

'yes' then -- Find the Roman numerals for the fractional parts of numbers. -- If num is not a whole number, add half of 1/1728 (the smallest unit) to equate to rounding. -- Ensure we're not less than the smallest unit or larger than 1 - smallest unit -- to avoid getting two "half" symbols or no symbols at all num = num - math.floor(num) if num ~= 0 then num = math.max(1.1/1728, math.min(1727.1/1728, num + 1/3456)) end local fractionalRomans = local fractionalLetters = getLetters(num, fractionalRomans) ret = ret .. fractionalLetters end

return retend

function p.main(frame) -- If called via #invoke, use the args passed into the invoking -- template, or the args passed to #invoke if any exist. Otherwise -- assume args are being passed directly in from the debug console -- or from another Lua module. local origArgs if frame

mw.getCurrentFrame then origArgs = frame:getParent.args for k, v in pairs(frame.args) do origArgs = frame.args break end else origArgs = frame end -- Trim whitespace and remove blank arguments. local args = for k, v in pairs(origArgs) do if type(v)

'string' then v = mw.text.trim(v) end if v ~= then args[k] = v end end -- exit if not given anything if args

nil or args

then return end -- Given mathematical expression, simplify to a number if type(args[1])

'string' then local success, result = pcall(mw.ext.ParserFunctions.expr, args[1]) if success then args[1] = result end -- else, pass to _main routine and try to let Lua's tonumber handle it end return _main(args)end

return p