# @turf/ellipse

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## ellipse

Takes a [Point][1] and calculates the ellipse polygon given two semi-axes expressed in variable units and steps for precision.

### Parameters

*   `center` **[Coord][2]** center point
*   `xSemiAxis` **[number][3]** semi (major) axis of the ellipse along the x-axis
*   `ySemiAxis` **[number][3]** semi (minor) axis of the ellipse along the y-axis
*   `options` **[Object][4]** Optional parameters (optional, default `{}`)

    *   `options.angle` **[number][3]** angle of rotation in decimal degrees, positive clockwise (optional, default `0`)
    *   `options.pivot` **[Coord][2]** point around which any rotation will be performed (optional, default `center`)
    *   `options.steps` **[number][3]** number of steps (optional, default `64`)
    *   `options.units` **[string][5]** unit of measurement for axes (optional, default `'kilometers'`)
    *   `options.properties` **[Object][4]** properties (optional, default `{}`)

### Examples

```javascript
var center = [-75, 40];
var xSemiAxis = 5;
var ySemiAxis = 2;
var ellipse = turf.ellipse(center, xSemiAxis, ySemiAxis);

//addToMap
var addToMap = [turf.point(center), ellipse]
```

Returns **[Feature][6]<[Polygon][7]>** ellipse polygon

[1]: https://tools.ietf.org/html/rfc7946#section-3.1.2

[2]: https://tools.ietf.org/html/rfc7946#section-3.1.1

[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

[6]: https://tools.ietf.org/html/rfc7946#section-3.2

[7]: https://tools.ietf.org/html/rfc7946#section-3.1.6

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---

This module is part of the [Turfjs project](https://turfjs.org/), an open source module collection dedicated to geographic algorithms. It is maintained in the [Turfjs/turf](https://github.com/Turfjs/turf) repository, where you can create PRs and issues.

### Installation

Install this single module individually:

```sh
$ npm install @turf/ellipse
```

Or install the all-encompassing @turf/turf module that includes all modules as functions:

```sh
$ npm install @turf/turf
```