Generalized Petersen graph generator

[haaninjo]

This patch introduces a generator for the generalized Petersen graphs.

http://mathworld.wolfram.com/GeneralizedPetersenGraph.html

http://en.wikipedia.org/wiki/Petersen_graph#Generalized_Petersen_graphs

The method used for plotting gives exactly the same result as the Petersen, Desargues, and the Moebius-Kantor graphs, so these functions have been simplified to just call GeneralizedPetersenGraph() with suitable parameter values and then change the graph's name to the named graph in question.

Patch is made against sage 4.1.2

Component: graph theory

Author: Anders Jonsson

Reviewer: Nathann Cohen

Merged: sage-4.2.alpha1

Issue created by migration from https://trac.sagemath.org/ticket/7228

[haaninjo]

generator for generalized Petersen graphs

[haaninjo]

comment:1

Attachment: trac_7228.patch.gz

[nathanncohen]

comment:2

This patch seems perfect to me ! I just modified the name of this graph so that it includes the values of n and k, and added some ` somewhere.

If you agree with these, you can set this ticket to positive review !

[haaninjo]

comment:3

Attachment: trac_7228-reviewer.patch.gz

Thanks for your review, I agree with all changes. I noticed however that my patch caused a test to fail in graph.py (a test that looks up the coordinates of all vertices of the Petersen Graph). The failure was trivial, the main reason was that I had placed the nodes at larger distance from (0,0) than before.

I have fixed these position issues in this new patch, which should be applied on top of trac_7228-reviewer.patch

[haaninjo]

Attachment: trac_7228-fix_positions.patch.gz

fixes failure of position test

[nathanncohen]

comment:4

good point !

Positive review !

[mwhansen]

Author: Anders Jonsson

[mwhansen]

Reviewer: Nathann Cohen

[mwhansen]

Merged: sage-4.2.alpha1