On Feb 24, 11:45 am, Martin Rubey <martin.ru...@math.uni-hannover.de> wrote: > At least from one point of view it makes sense to make such a choice: > when you do, the incidence matrix times it's transpose gives you the > Laplace matrix of the graph.
That's a good point. > Thus if you indeed change this behaviour, it may make sense to add a > method that imposes an arbitrary ordering. What if instead you were able to convert a graph to an "underlying" digraph and then ask for the incidence matrix of the resulting digraph? Right now, if you pass a graph as the argument when creating a digraph, the digraph you create has directed edges in both directions everywhere there is an undirected edge. At least two commands on graphs return a digraph: minimum_outdegree_orientation() and strong_orientation(). Maybe a digraph with an arbitrary direction can be created from a graph as part of initializing a digraph (with a keyword argument to distinguish getting both directions) or a separate function could be created to produce a digraph from a graph (possibly with keyword arguments controlling the way "arbitrary" is implemented)? Rob -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
