mathjs/docs/reference/functions/re.md

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

# Function re

Get the real part of a complex number.
For a complex number `a + bi`, the function returns `a`.

For matrices, the function is evaluated element wise.


## Syntax

```js
math.re(x)
```

### Parameters

Parameter | Type | Description
--------- | ---- | -----------
`x` | Number | BigNumber | Complex | Array | Matrix | Boolean | null |  A complex number or array with complex numbers

### Returns

Type | Description
---- | -----------
Number | BigNumber | Array | Matrix | The real part of x


## Examples

```js
var a = math.complex(2, 3);
math.re(a);                     // returns Number 2
math.im(a);                     // returns Number 3

math.re(math.complex('-5.2i')); // returns Number 0
math.re(math.complex(2.4));     // returns Number 2.4
```


## See also

[im](im.md),
[conj](conj.md),
[abs](abs.md),
[arg](arg.md)


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