lua-big-number

A simple big number library for Lua, inspired by https://github.com/Patashu/break_infinity.js

Features

1. floating-point precision in the range [~e-e14 - ~ee14]
2. Hard limit should be about ee308, or 10^2¹⁰²⁴
3. method names identical or very similar to https://github.com/Patashu/break_infinity.js
4. non-mutable methods -> easy chaining Big:new(2):add(Big:new(2)):mul(Big:new(2))
5. Operator overloading Big:new(3) * Big:new(5) ^ 2
6. Notations like Standard, Scientific and Letters. Easily create your own

Usage

1. Add bignumber.lua into your project
2. Big = dofile("/path/to/bignumber.lua") or require "lua-big-number"

Example

require "lua-big-number"

local big1 = Big:new(100)
local big2 = Big:new(10)
local added = big1:add(big2)
print(added) -- will output 1.1e2
print(big1 * big2) -- will output 1.0e3
print(big1 + (big1 * big2 - big2) / (big1 ^ 0.4)) -- will output 2.5690442605365e2

-- comparisons
print(big1 > big2) -- true
print(big1 == big2) -- false

-- You can define a shorthand for Big:new()
local N = function(n) return Big:new(n) end

print(N(2) ^ 4096 / N("4.3e401")) -- 2.4288113521237e831

Notations

This library also comes with notation support. Notations are just functions composed together.

Example:

require "lua-big-number"
require "lua-big-number.notations"

print(Notations.Standard(Big:new(111222333))) -- will output 111.22 M
print(Notations.Letters(Big:new(-43987.654))) -- will output -43.99a
print(Notations.Scientific(Big:new(556677))) -- will output 5.57e5

-- Notations under "Notations." don't take configuration
-- parameters. Instead, build your own notation.
-- It's pretty simple. Use Notations.Components,
-- which are just functions.

---@param n Big
---@return string
local function MyNotation(n)
    local precision = 2 - (n.e % 3)
    local seq = { "", "My", "Own", "Custom", "Units" }
    -- The building blocks are under Notations.Components
    return Notations.Components.Mantissa(n, { precision = precision }) .. " " .. Notations.Components.Sequence(n, { sequence = seq })
end

print(MyNotation(Big:new(12345678))) -- will output "12.3 Own"