https://github.com/aboks/power-iteration

Implementation of the Power Iteration method for finding eigenvalues of a matrix, using math-php
https://github.com/aboks/power-iteration

eigenvalues eigenvectors linear-algebra mathematics php

Last synced: about 2 months ago
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Implementation of the Power Iteration method for finding eigenvalues of a matrix, using math-php

• Host: GitHub
• URL: https://github.com/aboks/power-iteration
• Owner: aboks
• License: mit
• Created: 2018-02-19T19:21:07.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2022-06-27T19:07:51.000Z (over 2 years ago)
• Last Synced: 2024-04-13T00:47:28.627Z (10 months ago)
• Topics: eigenvalues, eigenvectors, linear-algebra, mathematics, php
• Language: PHP
• Size: 41 KB
• Stars: 3
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
![Continuous Integration](https://github.com/aboks/power-iteration/workflows/Continuous%20Integration/badge.svg)

[![Latest Stable Version](https://poser.pugx.org/aboks/power-iteration/v/stable)](https://packagist.org/packages/aboks/power-iteration)

PowerIteration

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

Implementation of the Power Iteration method for finding (dominant) eigenvalues and the corresponding eigenvectors of a matrix, using the excellent [math-php](https://github.com/markrogoyski/math-php) library.

 

Installation

------------

Install using composer:

```

$ composer require aboks/power-iteration

```

Basic usage

-----------

```php

getDominantEigenpair(MatrixFactory::create([

    [2, 1],

    [0, 1]

 ]));

var_dump($dominant_eigenpair->getEigenvalue()); // 2

var_dump($dominant_eigenpair->getEigenvector()); // Vector([1, 0]), or a scalar multiple

```

Advanced usage

--------------

### Calculating the least dominant eigenpair

In most situations, one is interested in the dominant eigenvalue and its corresponding eigenvector. It is also possible to calculate the least dominant eigenpair however: 

```php

getLeastDominantEigenpair(MatrixFactory::create([

    [2, 1],

    [0, 1]

 ]));

var_dump($dominant_eigenpair->getEigenvalue()); // 1

var_dump($dominant_eigenpair->getEigenvector()); // Vector([√2, -√2]), or a scalar multiple

```

Customizations

--------------

### Stopping criterion

By default, the power iteration runs for 1000 iterations. The stopping criterion can be altered by passing an instance of `StoppingCriterion` as the first argument to `PowerIteration`:

```php