Perceptron.php

<?php
class Perceptron
{
    private $weights;

    public function __construct($n)
    {
        for ($i=0; $i<$n; $i++) {
            $this->weights[$i] = rand()/getrandmax()-0.5;
        }
    }

    public function feedforward(array $inputs)
    {
        return $this->activate(
            array_sum(
                array_map(
                    function($a,$b) {return $a * $b;},
                    $inputs,
                    $this->weights
                )
            )
        );
    }

    private function activate($sum)
    {
        return $sum > 0 ? 1 : -1;
    }

    public function learn(array $inputs, $error)
    {
        $c = 0.01;
        $this->weights = array_map(
            function($weight, $input) use ($error, $c) {
                return $weight + $c * $error * $input;
            },
            $this->weights,
            $inputs
        );
    }
}

Trainer.php

<?php
class Trainer
{
    public function desired($inputs) {

        list($x,$y) = $inputs;

        return $y > (2 * $x + 1) ? 1 : -1;
    }

    public function generateInputs()
    {
        return [
            rand()/getrandmax()*1000-500,
            rand()/getrandmax()*1000-500,
            1
        ];
    }

    public function train($perceptron, $inputs)
    {
        $desired = $this->desired($inputs);

        //echo "La bonne réponse est : {$desired}\n";

        $guess = $perceptron->feedforward($inputs);

        //echo "Le perceptron pense que c'est {$guess}\n";

        $error = $desired - $guess;

        //echo "L'erreur est de : {$error}\n";

        $perceptron->learn(
            $inputs,
            $error
        );
    }
}

training.php

<?php
$p = new Perceptron(3);
$t = new Trainer();

$note_max = 20;
$interro = [];
for($i=0; $i<$note_max; $i++) {
  $interro[] = $t->generateInputs();
}

// Évaluation
$errors = 0;
foreach ($interro as $exercice) {

    $guess = $p->feedforward($exercice);
    $desired = $t->desired($exercice);
    $errors += ($desired - $guess) > 0 ? 1 : 0;
}

$note = $note_max - $errors;
echo "Le perceptron a eu {$note}/{$note_max}\n";

// Entrainement
for($i=0;$i<10000;$i++) {

    $exercice = $t->generateInputs();
    $t->train($p, $exercice);
}

// Évaluation
$errors = 0;
foreach ($interro as $exercice) {

    $guess = $p->feedforward($exercice);
    $desired = $t->desired($exercice);

    $errors += ($desired - $guess) > 0 ? 1 : 0;
}
$note = $note_max - $errors;
echo "Le perceptron a eu {$note}/{$note_max}\n";