Module:Radix

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

local r = {}

r.decimal_to = function(frame)
	-- Get number (in base 10)
	decimal = tonumber(frame.args[1])
	-- If decimal is 0 or 1, return decimal
	if decimal == 0 or decimal == 1 then 
		return tostring(decimal)
	end
	
	-- Separator
	format_output = format_output and format_output or true
	thousands = thousands and thousands or ","
	point = point and point or "."
	
	-- Get radix to convert to
	radix = tonumber(frame.args[2])
	-- sign is equal to sign(decimal) if radix is positive, and 1 otherwise
	sign = radix > 0 and decimal / math.abs(decimal) or 1
	-- If radix is not an integer: Round to nearest integer for now
	radix = radix < 0 and math.ceil(radix) or math.floor(radix)
	-- If abs(radix) is 1, 0, or > 36, return decimal 
	if radix == 0 or math.abs(radix) == 1 or math.abs(radix) > 36 then 
		return tostring(decimal)
	end
	
	-- characters are based on other proglangs' parsing
	characters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	
	-- precision is the number of digits below 1 to use
	-- if decimal is less than 1/radix ^ precision, return 0
	precision = tonumber(frame.args[3]) or 0
	minpower = radix ^ (precision * -1)
	if decimal < minpower then
		return "0"
	end
	
	-- arrays of digits
	digits = {}
	digitchars = {}
	
	-- maxpower calculation
	maxpower = 1
	while math.abs(maxpower) < math.abs(decimal) do
		maxpower = maxpower * radix
	end
	-- if decimal < 0 then maxpower should be 1
	
	-- calculate digits
	digitval = maxpower
	i = 1
	-- format radix and set up num of integral digits for possible formatting
	if radix > 0 then decimal = math.abs(decimal) end
	integrals = 0
	while math.abs(digitval) >= math.abs(minpower) do
		-- get floor of abs(decimal) / abs (digitval)
		thisdigit = math.floor(math.abs(decimal) / math.abs(digitval))
		-- if i is 1 and thisdigit is 0:
		-- if radix is negative, add 1 to thisdigit
		-- if radix is positive and maxpower isn't 1, skip
		add_digit = true
		if thisdigit == 0 and i == 1 then
			if radix < 0 then
				thisdigit = 1
			elseif maxpower > 1 then
				add_digit = false
			end
		end
		if add_digit then
			-- add thisdigit to digits
			digits[i] = thisdigit
			-- subtract thisdigit * digitval from decimal
			decimal = decimal - (thisdigit * digitval)
			if digitval >= 1 then integrals = integrals + 1 end
			digitval = digitval / radix
			i = i + 1
		end
	end
	
	-- if sign is -1, append a negative sign to the front
	signchar = sign == -1 and "" or "-"
	ret = "" .. signchar
	
	-- assemble digits
	separators = 0
	distance = math.abs(radix) <= 6 and 3 or 4
	for j,digit in ipairs(digits) do
		ret = ret .. string.sub(characters, digit+1, digit+1)
		-- when integrals - j is a positive multiple of distance
		if format_output then
			if j < integrals and (integrals - j) % distance == 0 then
				-- add "," and 1 to separators
				separators = separators + 1
				ret = ret .. thousands
			end
		end
		-- when j equals integrals
		if j == integrals then
			-- add "." and 1 to separators
			separators = separators + 1
			ret = ret .. point
		end
	end
	return ret
end

return r