public function getRules()
{
return array('d' => array('format_positive' => '%v%s', 'format_negative' => '-%v%s', 'symbol' => '°'), 'r' => array('symbol' => 'pi', 'rate' => function ($value, $ruleTo) {
if ($ruleTo === 'd') {
return $value * 180;
}
return $value / 180;
}), 'g' => array('symbol' => 'Grad', 'rate' => function ($value, $ruleTo) {
if ($ruleTo === 'd') {
return $value * 0.9;
}
return $value / 0.9;
}), 't' => array('symbol' => 'Turn', 'rate' => 360));
}