graph_2_mat - node-arc or node-node incidence matrix of a graph
graph_2_mat computes the node-arc or the node-node incidence matrix corresponding to the graph g.
If the optional argument mat is omitted or is the string 'node-arc', the node-arc matrix is computed. If mat is the string 'node-node', the node-node matrix is computed.
If n is the number of nodes of the graph and m is the number of edges of the graph, the node-arc matrix is a Scilab sparse matrix of size (n,m).
It is defined as follows. If the graph is directed:
a(i,j) = +1 if node i is the tail of arc j
a(i,j) = -1 if node i is the head of arc j
If the graph is undirected:
a(i,j) = 1 if node i is the tail or the head of arc j
If n is the number of nodes of the graph, the node-node matrix is a Scilab sparse matrix of size (n,n).
It is defined as follows:
a(i,j) = 1 if there is an arc from node i to node j
g=load_graph(SCI+'/demos/metanet/colored'); a=graph_2_mat(g) a=graph_2_mat(g,'node-node')