https://github.com/mikolalysenko/robust-in-sphere

Exact arithmetic test to check if (n+2) points are cospherical
https://github.com/mikolalysenko/robust-in-sphere

Last synced: about 2 months ago
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Exact arithmetic test to check if (n+2) points are cospherical

• Host: GitHub
• URL: https://github.com/mikolalysenko/robust-in-sphere
• Owner: mikolalysenko
• License: mit
• Created: 2013-10-22T23:07:22.000Z (about 11 years ago)
• Default Branch: master
• Last Pushed: 2021-08-04T23:24:56.000Z (over 3 years ago)
• Last Synced: 2024-10-20T14:27:08.579Z (2 months ago)
• Language: JavaScript
• Size: 14.6 KB
• Stars: 11
• Watchers: 4
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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robust-in-sphere

================

Exact arithmetic test to check if (n+2) points are cospherical.

(Very) loosely inspired by [Jonathan Shewchuk's work on robust predicates](http://www.cs.cmu.edu/~quake/robust.html).  Currently not as fast, but pull requests are welcome.

[![testling badge](https://ci.testling.com/mikolalysenko/robust-in-sphere.png)](https://ci.testling.com/mikolalysenko/robust-in-sphere)

[![build status](https://secure.travis-ci.org/mikolalysenko/robust-in-sphere.png)](http://travis-ci.org/mikolalysenko/robust-in-sphere)

# Example

```javascript

var inSphere = require("robust-in-sphere")

console.log(inSphere(

  [0, 1],

  [1, 0],

  [-1, 0],

  [0, -1]))

```

# Install

```

npm install robust-in-sphere

```

# API

```javascript

var inSphere = require("robust-in-sphere")

```

### `inSphere(a,b,c,...)`

Tests if a collection of `n+2` points in `n`-dimensional space are cospherical or if the last point is contained in the sphere or not.

* `a,b,c,...` is a list of points

**Returns** A signed integer that gives the orientation of the points

* `<0` if the last point is contained in the oriented sphere defined by the previous two points

* `>0` if the last point is outside the sphere

* `0` is the points are cospherical

**Notes** Up to 6 points it is possible to get a specialized version of `inSphere` that avoids an extra dispatch using the syntax:

```javascript

inSphere[4](a,b,c,d) === inSphere(a,b,c,d)

```

## Credits

(c) 2014 Mikola Lysenko. MIT License