protected function getNormalizedNumbers($args)
{
$unit = null;
$originalUnit = null;
$numbers = array();
foreach ($args as $key => $item) {
if ('number' != $item[0]) {
$this->throwError("%s is not a number", $item[0]);
}
$number = $this->normalizeNumber($item);
if (null === $unit) {
$unit = $number[2];
$originalUnit = $item[2];
} elseif ($unit !== $number[2]) {
$this->throwError('Incompatible units: "%s" and "%s".', $originalUnit, $item[2]);
}
$numbers[$key] = $number;
}
return $numbers;
}