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README.md
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An arbitrary-precision Decimal type for JavaScript. An arbitrary-precision Decimal type for JavaScript.
*WARNING: Version 5 brings significant API changes (see CHANGELOG). Version 4 will continue to be supported.* <br>
<br>
[![Build Status](https://travis-ci.org/MikeMcl/decimal.js.svg)](https://travis-ci.org/MikeMcl/decimal.js) [![Build Status](https://travis-ci.org/MikeMcl/decimal.js.svg)](https://travis-ci.org/MikeMcl/decimal.js)
*For a smaller library without the trigonometric functions see the
[v4.x.x](https://github.com/MikeMcl/decimal.js/tree/v4.x.x) branch where version 4 of this library
continues to be supported, or see [decimal.js-light](https://github.com/MikeMcl/decimal.js-light/), which is smaller still.*
<br>
## Features ## Features
- Integers and floats - Integers and floats
- Simple but full-featured API - Simple but full-featured API
- Replicates many of the methods of JavaScript's `Number.prototype` and `Math` objects - Replicates many of the methods of JavaScript's `Number.prototype` and `Math` objects
- Also handles hexadecimal, binary and octal values - Also handles hexadecimal, binary and octal values
- Supports serialization of Decimals to a compact base-88 format for transmission or persistence - Supports serialization of Decimals to a compact base-88 format for transmission or persistence
- Faster, smaller, and perhaps easier to use than JavaScript versions of Java's BigDecimal - Faster, smaller, and perhaps easier to use than JavaScript versions of Java's BigDecimal
- No dependencies - No dependencies
- Wide platform compatibility: uses JavaScript 1.5 (ECMAScript 3) features only - Wide platform compatibility: uses JavaScript 1.5 (ECMAScript 3) features only
@ -25,34 +29,40 @@ precision is specified in terms of significant digits instead of decimal places,
calculations are rounded to the precision (similar to Python's decimal module) rather than just calculations are rounded to the precision (similar to Python's decimal module) rather than just
those involving division. those involving division.
This library also adds the trigonometric functions, among others, and supports non-integer powers. This library also adds the trigonometric functions, among others, and supports non-integer powers,
which makes it a significantly larger library than *bignumber.js* and the even smaller
Another major difference is that this library enables multiple Decimal constructors to be created [big.js](https://github.com/MikeMcl/big.js/).
each with their own configuration. This is, however, a significantly larger library than
*bignumber.js* and the even smaller [big.js](https://github.com/MikeMcl/big.js/).
## Load ## Load
The library is the single JavaScript file *decimal.js* (or minified, *decimal.min.js*). The library is the single JavaScript file *decimal.js* (or minified, *decimal.min.js*).
It can be loaded using a script tag in an HTML document for the browser It can be loaded using a script tag in an HTML document for the browser
```html ```html
<script src='path/to/decimal.js'></script> <script src='path/to/decimal.js'></script>
``` ```
or as a [Node.js](http://nodejs.org) module using `require`. or as a [Node.js](http://nodejs.org) module using `require`.
```javascript
```js
var Decimal = require('decimal'); var Decimal = require('decimal');
``` ```
For Node, the library is available from the [npm](https://npmjs.org/) registry For Node, the library is available from the [npm](https://npmjs.org/) registry
```bash ```bash
$ npm install decimal.js $ npm install decimal.js
``` ```
To load with AMD loader libraries such as [requireJS](http://requirejs.org/): To load with AMD loader libraries such as [requireJS](http://requirejs.org/):
```javascript
```js
require(['decimal'], function(Decimal) { require(['decimal'], function(Decimal) {
// Use Decimal here in local scope. No global Decimal. // Use Decimal here in local scope. No global Decimal.
}); });
``` ```
## Use ## Use
*In all examples below, `var`, semicolons and `toString` calls are not shown. *In all examples below, `var`, semicolons and `toString` calls are not shown.
@ -61,74 +71,93 @@ If a commented-out value is in quotes it means `toString` has been called on the
The library exports a single function object, `Decimal`, the constructor of Decimal instances. The library exports a single function object, `Decimal`, the constructor of Decimal instances.
It accepts a value of type number, string or Decimal. It accepts a value of type number, string or Decimal.
```javascript
```js
x = new Decimal(123.4567) x = new Decimal(123.4567)
y = new Decimal('123456.7e-3') y = new Decimal('123456.7e-3')
z = new Decimal(x) z = new Decimal(x)
x.equals(y) && y.equals(z) && x.equals(z) // true x.equals(y) && y.equals(z) && x.equals(z) // true
``` ```
A value can also be in binary, hexadecimal or octal if the appropriate prefix is included. A value can also be in binary, hexadecimal or octal if the appropriate prefix is included.
```javascript
```js
x = new Decimal('0xff.f') // '255.9375' x = new Decimal('0xff.f') // '255.9375'
y = new Decimal('0b10101100') // '172' y = new Decimal('0b10101100') // '172'
z = x.plus(y) // '427.9375' z = x.plus(y) // '427.9375'
z.toBinary() // '0b110101011.1111' z.toBinary() // '0b110101011.1111'
z.toBinary(13) // '0b1.101010111111p+8' z.toBinary(13) // '0b1.101010111111p+8'
``` ```
A Decimal is immutable in the sense that it is not changed by its methods. A Decimal is immutable in the sense that it is not changed by its methods.
```javascript
```js
0.3 - 0.1 // 0.19999999999999998 0.3 - 0.1 // 0.19999999999999998
x = new Decimal(0.3) x = new Decimal(0.3)
x.minus(0.1) // '0.2' x.minus(0.1) // '0.2'
x // '0.3' x // '0.3'
``` ```
The methods that return a Decimal can be chained. The methods that return a Decimal can be chained.
```javascript
```js
x.dividedBy(y).plus(z).times(9).floor() x.dividedBy(y).plus(z).times(9).floor()
x.times('1.23456780123456789e+9').plus(9876.5432321).dividedBy('4444562598.111772').ceil() x.times('1.23456780123456789e+9').plus(9876.5432321).dividedBy('4444562598.111772').ceil()
``` ```
Many method names have a shorter alias. Many method names have a shorter alias.
```javascript
```js
x.squareRoot().dividedBy(y).toPower(3).equals(x.sqrt().div(y).pow(3)) // true x.squareRoot().dividedBy(y).toPower(3).equals(x.sqrt().div(y).pow(3)) // true
x.cmp(y.mod(z).neg()) == 1 && x.comparedTo(y.modulo(z).negated()) == 1 // true x.cmp(y.mod(z).neg()) == 1 && x.comparedTo(y.modulo(z).negated()) == 1 // true
``` ```
Like JavaScript's Number type, there are `toExponential`, `toFixed` and `toPrecision` methods, Like JavaScript's Number type, there are `toExponential`, `toFixed` and `toPrecision` methods,
```javascript
```js
x = new Decimal(255.5) x = new Decimal(255.5)
x.toExponential(5) // '2.55500e+2' x.toExponential(5) // '2.55500e+2'
x.toFixed(5) // '255.50000' x.toFixed(5) // '255.50000'
x.toPrecision(5) // '255.50' x.toPrecision(5) // '255.50'
``` ```
and many of the methods of JavaScript's Math object are also replicated.
```javascript and almost all of the methods of JavaScript's Math object are also replicated.
```js
Decimal.sqrt('6.98372465832e+9823') // '8.3568682281821340204e+4911' Decimal.sqrt('6.98372465832e+9823') // '8.3568682281821340204e+4911'
Decimal.pow(2, 0.0979843) // '1.0702770511687781839' Decimal.pow(2, 0.0979843) // '1.0702770511687781839'
``` ```
There are `isNaN` and `isFinite` methods, as `NaN` and `Infinity` are valid `Decimal` values, There are `isNaN` and `isFinite` methods, as `NaN` and `Infinity` are valid `Decimal` values,
```javascript
```js
x = new Decimal(NaN) // 'NaN' x = new Decimal(NaN) // 'NaN'
y = new Decimal(Infinity) // 'Infinity' y = new Decimal(Infinity) // 'Infinity'
x.isNaN() && !y.isNaN() && !x.isFinite() && !y.isFinite() // true x.isNaN() && !y.isNaN() && !x.isFinite() && !y.isFinite() // true
``` ```
and a `toFraction` method with an optional *maximum denominator* argument and a `toFraction` method with an optional *maximum denominator* argument
```javascript
```js
z = new Decimal(355) z = new Decimal(355)
pi = z.dividedBy(113) // '3.1415929204' pi = z.dividedBy(113) // '3.1415929204'
pi.toFraction() // [ '7853982301', '2500000000' ] pi.toFraction() // [ '7853982301', '2500000000' ]
pi.toFraction(1000) // [ '355', '113' ] pi.toFraction(1000) // [ '355', '113' ]
``` ```
All calculations are rounded according to the number of significant digits and rounding mode
specified by the `precision` and `rounding` properties of the Decimal constructor.
As mentioned above, multiple Decimal constructors can be created, each with their own independent All calculations are rounded according to the number of significant digits and rounding mode
configuration which applies to all Decimal numbers created from it. specified by the `precision` and `rounding` properties of the Decimal constructor.
```javascript
Multiple Decimal constructors can be created, each with their own independent configuration which
applies to all Decimal numbers created from it.
```js
// Set the precision and rounding of the default Decimal constructor // Set the precision and rounding of the default Decimal constructor
Decimal.config({ precision: 5, rounding: 4 }) Decimal.config({ precision: 5, rounding: 4 })
// Create another Decimal constructor, optionally passing in a configuration object // Create another Decimal constructor, optionally passing in a configuration object
Decimal10 = Decimal.clone({ precision: 10, rounding: 1 }) Decimal10 = Decimal.clone({ precision: 10, rounding: 1 })
x = new Decimal(5) x = new Decimal(5)
y = new Decimal10(5) y = new Decimal10(5)
@ -136,30 +165,39 @@ y = new Decimal10(5)
x.div(3) // '1.6667' x.div(3) // '1.6667'
y.div(3) // '1.666666666' y.div(3) // '1.666666666'
``` ```
The value of a Decimal is stored in a floating point format in terms of its digits, exponent and sign. The value of a Decimal is stored in a floating point format in terms of its digits, exponent and sign.
```javascript
```js
x = new Decimal(-12345.67); x = new Decimal(-12345.67);
x.d // [ 12345, 6700000 ] digits (base 10000) x.d // [ 12345, 6700000 ] digits (base 10000000)
x.e // 4 exponent (base 10) x.e // 4 exponent (base 10)
x.s // -1 sign x.s // -1 sign
``` ```
For further information see the [API](http://mikemcl.github.io/decimal.js/) reference in the *doc* directory. For further information see the [API](http://mikemcl.github.io/decimal.js/) reference in the *doc* directory.
## Test ## Test
The library can be tested using Node.js or a browser. The library can be tested using Node.js or a browser.
The *test* directory contains the file *test.js* which runs all the tests when executed by Node, and the file *test.html* which runs all the tests when opened in a browser. The *test* directory contains the file *test.js* which runs all the tests when executed by Node,
and the file *test.html* which runs all the tests when opened in a browser.
To run all the tests, from a command-line at the root directory using npm To run all the tests, from a command-line at the root directory using npm
```bash ```bash
$ npm test $ npm test
``` ```
or at the *test* directory using Node or at the *test* directory using Node
```bash
```bash
$ node test $ node test
``` ```
Each separate test module can also be executed individually, for example, at the *test/modules* directory Each separate test module can also be executed individually, for example, at the *test/modules* directory
```bash ```bash
$ node toFraction $ node toFraction
``` ```
@ -167,13 +205,17 @@ $ node toFraction
## Build ## Build
For Node, if [uglify-js](https://github.com/mishoo/UglifyJS2) is installed For Node, if [uglify-js](https://github.com/mishoo/UglifyJS2) is installed
```bash ```bash
npm install uglify-js -g npm install uglify-js -g
``` ```
then then
```bash ```bash
npm run build npm run build
``` ```
will create *decimal.min.js*, and a source map will also be added to the *doc* directory. will create *decimal.min.js*, and a source map will also be added to the *doc* directory.
## Feedback ## Feedback