PHP code example of aboks / power-iteration

1. Go to this page and download the library: Download aboks/power-iteration library. Choose the download type require.

2. Extract the ZIP file and open the index.php.

3. Add this code to the index.php. 
    
        
<?php
require_once('vendor/autoload.php');

/* Start to develop here. Best regards https://php-download.com/ */

aboks / power-iteration example snippets



use Aboks\PowerIteration\PowerIteration;
use MathPHP\LinearAlgebra\MatrixFactory;

$power_iteration = new PowerIteration();
$dominant_eigenpair = $power_iteration->getDominantEigenpair(MatrixFactory::create([
    [2, 1],
    [0, 1]
 ]));
var_dump($dominant_eigenpair->getEigenvalue()); // 2
var_dump($dominant_eigenpair->getEigenvector()); // Vector([1, 0]), or a scalar multiple



use Aboks\PowerIteration\PowerIteration;
use MathPHP\LinearAlgebra\Matrix;

$power_iteration = new PowerIteration();
$dominant_eigenpair = $power_iteration->getLeastDominantEigenpair(MatrixFactory::create([
    [2, 1],
    [0, 1]
 ]));
var_dump($dominant_eigenpair->getEigenvalue()); // 1
var_dump($dominant_eigenpair->getEigenvector()); // Vector([√2, -√2]), or a scalar multiple



use Aboks\PowerIteration\PowerIteration;
use Aboks\PowerIteration\StoppingCriterion\MaxIterations;
use Aboks\PowerIteration\StoppingCriterion\EigenvectorTolerance;

new PowerIteration(new MaxIterations(10));           // will stop after 10 iterations
new PowerIteration(new EigenvectorTolerance(0.01));  // will stop when ‖Av - λv‖ < 0.01



use Aboks\PowerIteration\PowerIteration;
use Aboks\PowerIteration\ScalingMethod\NormBased;
use Aboks\PowerIteration\Norm\MaxNorm;

new PowerIteration(null, new NormBased(new MaxNorm()));  // will scale to a unit vector based on the max-norm