Definition:  for a network containing n nodes and b branches and in which a reference direction is chosen for each branch, matrix of type n × b where the element a_{ij} is:
 0 if branch j is not incident at node i
 1 if branch j is pointing away from node i
 −1 if branch j is pointing towards node i
NOTE – The figure below gives a network and the corresponding branchnode incidence matrix.
