mathjs/docs/reference/functions/config.md

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# Function config

Set configuration options for math.js, and get current options.
Will emit a 'config' event, with arguments (curr, prev, changes).

This function is only available on a mathjs instance created using `create`.


## Syntax

```js
math.config(config: Object): Object
```

### Parameters

Parameter | Type | Description
--------- | ---- | -----------
`options` | Object | Available options: {number} epsilon Minimum relative difference between two compared values, used by all comparison functions. {string} matrix A string 'Matrix' (default) or 'Array'. {string} number A string 'number' (default), 'BigNumber', or 'Fraction' {number} precision The number of significant digits for BigNumbers. Not applicable for Numbers. {string} parenthesis How to display parentheses in LaTeX and string output. {string} randomSeed Random seed for seeded pseudo random number generator. Set to null to randomly seed.

### Returns

Type | Description
---- | -----------
Object | Returns the current configuration


## Examples

```js
import { create, all } from 'mathjs'

// create a mathjs instance
const math = create(all)

math.config().number                // outputs 'number'
math.evaluate('0.4')                // outputs number 0.4
math.config({number: 'Fraction'})
math.evaluate('0.4')                // outputs Fraction 2/5
```