A chord subgroup serving as source or target of a chord between two nodes i an j (where i may be equal to j).
End angle of the chord subgroup in radians
The node index i
Start angle of the chord subgroup in radians
The flow value in matrix[i][j] from node i to node j
A chord subgroup serving as source or target of a chord between two nodes i an j (where i may be equal to j).