ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Fri, 13 Feb 2015 01:32:19 +0100Sage+Gurobi: Can I control how many processors vertex_coloring uses?https://ask.sagemath.org/question/25819/sagegurobi-can-i-control-how-many-processors-vertex_coloring-uses/I am using Sage to color some graphs, using a 32-processor Linux server. I am using the vertex_coloring command, with Gurobi as the LP solver.
I've noticed that for graphs that take more than a few minutes, the program seems to eventually settle on using 16 processors. It would be nice if I could tell Sage (or Gurobi?) to allow more or fewer processors. Is this possible?
MattKahleFri, 13 Feb 2015 01:32:19 +0100https://ask.sagemath.org/question/25819/Is there a bug with using chromatic_number together with Gurobi?https://ask.sagemath.org/question/25564/is-there-a-bug-with-using-chromatic_number-together-with-gurobi/I have installed the LP solver Gurobi, and it seems to work successfully work with the vertex_coloring() command. But I wanted to compare runtimes with chromatic_number, and Sage seems to hang whenever I try this.
I construct a graph G, and then when I run the command G.chromatic_number(algorithm="MILP"), Sage hangs. I can tell something has gone wrong because it doesn't come back even when I give it a very small simple graph G, and because Linux tells me that I know have a zombie process.
Any suggestions would be much appreciated.
MattKahleMon, 19 Jan 2015 22:19:01 +0100https://ask.sagemath.org/question/25564/