public function toArray()
	{
		$a = array();
		$nodes = $this->getNodes();
		for( $i=0; $i<$this->getNodeSize(); $i++ )
		{
			$source = $nodes[$i];
			$line = array();
			for( $j=0; $j<$this->getNodeSize(); $j++ )
			{
				$target = $nodes[$j];
				$value = $this->getEdgeValue( $source, $target );
				$line[$target->getNodeName()] = $value;
			}
			$a[$source->getNodeName()] = $line;
		}
		return $a;
	}