How can I convert all values of an array to floats in PHP?

$floats = array_map('floatval', $nonFloats);

function toFloats($array)
{
    return array_map('floatval', $array);
}

$data = array_map('toFloats', $my2DArray);

protected function _c2f($input)
    {
        $input = (float)$input;
        $output = round(($input * 1.8) + 32, 2);

        return $output;
    }