Base N in Lua

gistfile1.lua

local floor,insert = math.floor, table.insert
local function basen(n,b)
    n = floor(n)
    if not b or b == 10 then return tostring(n) end
    local digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
    local t = {}
    local sign = ""
    if n < 0 then
        sign = "-"
    n = -n
    end
    repeat
        local d = (n % b) + 1
        n = floor(n / b)
        insert(t, 1, digits:sub(d,d))
    until n == 0
    return sign .. table.concat(t,"")
end