func (g *DirectedDenseGraph) SetEdgeWeight(e graph.Edge) {
fid := e.From().ID()
tid := e.To().ID()
if fid == tid {
panic("concrete: set edge cost of illegal edge")
}
g.mat.Set(fid, tid, e.Weight())
}
// SetEdge sets e, an edge from one node to another. If the ends of the edge are not in g
// or the edge is a self loop, SetEdge panics.
func (g *DirectedMatrix) SetEdge(e graph.Edge) {
fid := e.From().ID()
tid := e.To().ID()
if fid == tid {
panic("simple: set illegal edge")
}
g.mat.Set(fid, tid, e.Weight())
}