/**
* Calculates a hidden node's delta based on the layer behind it.
*
* @param PerceptronInterface $perceptron The perceptron in which we calculate.
* @param Node $subject The subjected node which weight gets recalculated.
* @param LayerInterface $behind The layer connected behind the subject.
* @return float The delta for the subject.
*/
public function calculateHiddenDelta(PerceptronInterface $perceptron, Node $subject, LayerInterface $behind)
{
// Calculate error by deltas from layer behind.
$error = PerceptronUtil::dot($perceptron->getOutgoingWeights($subject), $behind->getDeltas());
return $this->calculateDelta($subject, $error);
}
/**
* @param LayerInterface $layerInFront
* @param Node $node
*/
private function updateNodesInFront(LayerInterface $layerInFront, Node $node)
{
$multi = $this->getLearningRate() * $node->delta;
foreach ($layerInFront->getNodes() as $nodeInFront) {
$deltaWeight = $multi * $nodeInFront->value;
$this->decreaseWeight($nodeInFront, $node, $deltaWeight);
}
}