https://github.com/munrocket/fixed-point

🗿 Fixed point arithmetic with BigInt. Minimalistic library for money calculation.
https://github.com/munrocket/fixed-point

Last synced: 3 days ago
JSON representation

🗿 Fixed point arithmetic with BigInt. Minimalistic library for money calculation.

• Host: GitHub
• URL: https://github.com/munrocket/fixed-point
• Owner: munrocket
• License: mit
• Created: 2021-10-05T08:17:52.000Z (about 3 years ago)
• Default Branch: main
• Last Pushed: 2021-11-02T22:54:07.000Z (about 3 years ago)
• Last Synced: 2024-10-10T05:35:20.853Z (27 days ago)
• Language: JavaScript
• Homepage:
• Size: 46.9 KB
• Stars: 4
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# 🗿 fixed-point

Fixed point arithmetic with BigInt. Minimalistic library for money or scientific calculations with known precision.

### Examples

Install package `npm install fixed-point` or include minified script on page.

```js

import { FixedPoint } from 'fixed-point';

// Simple example: 0.3 - 0.2 = 0.1

console.log(new FixedPoint(0.3).sub(0.2).toString());

// Price with 30% discount, rounding benefiting the customer

FixedPoint.setRounding('floor');

console.log(new FixedPoint('99.95').mul(0.70).toFixed())

// Bitcoin fee with banker rounding: 1.0 BTC - 0.00005 BTC = 0.99995000 BTC  

FixedPoint.setRounding('even');

FixedPoint.setPrecision(8);

console.log(new FixedPoint('1').sub('0.00005').toFixed() + ' BTC');

// Rounding mode for fast calculations

FixedPoint.setRounding('trunc');

FixedPoint.setPrecision(15);

console.log(new FixedPoint('3.14159265358979').mul('2'));

```

### API

* `new FixedPoint(string)` - constructor from String

* `new FixedPoint(number)` - constructor from Number

* `a.toString()` - conversion to String

* `a.toFixed()` - conversion to String

* `FixedPoint.setPrecision(number)` - set precision (2 decimal places is default)

* `FixedPoint.setRounding(string)` - set rounding ('trunc'|'floor'|'ceil'|'even'), 'even' is default

* `a.add(b)` - addition (exact)

* `a.sub(b)` - subtraction (exact)

* `a.mul(b)` - multiplication (rounded)

* `a.div(b)` - division (rounded)

* `a.eq(b)` - `a == b`

* `a.ne(b)` - `a != b`

* `a.gt(b)` - `a > b`

* `a.ge(b)` - `a >= b`

* `a.lt(b)` - `a < b`

* `a.le(b)` - `a <= b`

### 2do

- [x] constructors, toString/toFixed

- [x] operations: +|-|*|/

- [x] 4 rounding modes from IEEE 754-1985: RN, RZ, RU, RD

- [x] testing rounding modes with table

- [x] get feedback

- [x] add benchmark

- [ ] add precision conversion: x.xxxxxxxx BTC in xx.xx $

- [ ] add build with BigInt polyfill

### Motivation

This library was inspired by conversion in decimal-proposal, also by Yaffle PR in extra-bigint