The time trouble starts at the point in the code where it doesn't matter where the permutation matrices comes from.
What the main part does is basically this. Given any set of matrices of dimensional k it produces by the "product" and "zip" command all possible ways of distributing those matrices over the set of edges of the graph of size n . One fixes some arbitrary orientation for each of the edges. It doesn't matter what. Now it creates a matrix M of size kn as a n x n array of size k matrices as follows : for the (a,b) edge is in the oriented edge list it (1) places into the (a,b) array position the matrix that was assigned to that edge and (2) it places into the (b,a) position the inverse of that matrix. Now it calculates the characteristic polynomial of this M and keeps adding it up over all possible ways of distributing the matrices over the edges. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
