ASKSAGE: Sage Q&A Forum - Latest question feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 30 Dec 2018 13:23:59 -0600Solve MILP by reading LP fileshttps://ask.sagemath.org/question/44817/solve-milp-by-reading-lp-files/Sage has a wide range of solvers available to [solve MILP](http://doc.sagemath.org/html/en/thematic_tutorials/linear_programming.html) problems. However, all these functionalities require that the problem is to be implemented following Sage's API.
In contrast, Gurobi allows to solve MILP problems, directly reading from an [LP file](http://www.gurobi.com/documentation/8.1/refman/lp_format.html). This comes in handy, as there's no need to follow Sage API. If the LP file is too large to handle, then the user can simply write another program that will create this file. Apart from being simple and scalable, LP formats can be used for porting to other (unsupported) library.
It seems that, Sage does not yet support directly reading LP files. It will be helpful if someone can comment specifically if such functionality is available or will be implemented in near future/a ticket can be initiated.ppSun, 30 Dec 2018 13:23:59 -0600https://ask.sagemath.org/question/44817/How do I set solver_parameter to make Gurobi use more than one processor?https://ask.sagemath.org/question/37726/how-do-i-set-solver_parameter-to-make-gurobi-use-more-than-one-processor/As [suggested previously](https://ask.sagemath.org/question/25819) by Nathann Cohen, the method `solver_parameter` allows to do such a thing
sage: p = MixedIntegerLinearProgram(solver = "Gurobi")
sage: p.solver_parameter?
In the [documentation](http://doc.sagemath.org/html/en/reference/numerical/sage/numerical/mip.html#sage.numerical.mip.MixedIntegerLinearProgram.solver_parameter) that appears, it says:
> Gurobi’s parameters should all be
> available through this method. Their
> list is available on Gurobi’s website
> http://www.gurobi.com/documentation/5.5/reference-manual/node798.
but this link is broken and leads us to http://www.gurobi.com/documentation/ instead. How do I set solver_parameter to make Gurobi use more than one processor?SébastienMon, 29 May 2017 06:29:29 -0500https://ask.sagemath.org/question/37726/Sage+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?
MattKahleThu, 12 Feb 2015 18:32:19 -0600https://ask.sagemath.org/question/25819/