Edit nodes and edges, then watch the adjacency matrix, Laplacian, and spectrum update instantly.
Click Add Node, then click the canvas to place one node.
Double-click Add Node to keep add-node mode on; click it again to turn it off.
By default, click a node to select and drag to move, or click an edge to select it. Press Delete or X to delete the selected node/edge.
In Toggle Edge mode: click two nodes to add/remove the undirected edge between them.