Module:ConvertMaxWidth

Documentation for this module may be created at Module:ConvertMaxWidth/doc

local p = {}

local function addCommas(n)
    local s = tostring(n)
    while true do
        s, k = s:gsub("^(-?%d+)(%d%d%d)", "%1,%2")
        if k == 0 then break end
    end
    return s
end

local function roundSigFig(num, sigfig)
    if num == 0 then return 0 end
    local scale = 10 ^ (sigfig - math.floor(math.log10(math.abs(num))) - 1)
    return math.floor(num * scale + 0.5) / scale
end

function p.main(frame)
    local args = frame.args

    local yards = tonumber(args[1])
    if not yards then
        return "Error: Invalid or missing yard value."
    end

    -- Default to 3 significant figures (matches Wikipedia)
    local sigfig = tonumber(args['sigfig']) or 3
    local abbr = args['abbr'] or 'on'

    -- Conversions (exact)
    local miles = yards / 1760
    local km = yards * 0.0009144

    -- Sig-fig rounding
    local milesR = roundSigFig(miles, sigfig)
    local kmR = roundSigFig(km, sigfig)

    local formattedYards = addCommas(math.floor(yards))
    local formattedMiles = tostring(milesR)
    local formattedKm = tostring(kmR)

    if abbr == 'on' then
    	return formattedYards .. " yards (" ..
           formattedMiles .. " mi; " ..
           formattedKm .. " km)"
	else
	return formattedYards .. " yards (" ..
           formattedMiles .. " miles; " ..
           formattedKm .. " kilometers)"
	end
end

return p