[Help-glpk] [Fwd: About reading the relative mip gap from the glp_prob C struct]

[Andrew Makhorin]

-------- Forwarded Message --------
From: Nathann Cohen <address@hidden>
To: GLPK help <address@hidden>, David Coudert
<address@hidden>
Subject: About reading the relative mip gap from the glp_prob C struct
Date: Wed, 26 Aug 2015 20:12:26 +0200

Hello everybody,

David Coudert and I are contributors to a software called Sagemath
[1], and we currently try to improve its interface with LP solvers,
among which is GLPK :-)

We would be very interested by a way to have in GLPK's C API, after a
call to glp_intopt, the value of the relative gap reached by the best
integer solution found so far.

Our problem is that this information, stored in the search tree
object, is erased when glp_intopt returns [2]. Would it be possible to
change the behaviour of glp_intopt and store it in the glp_prob C
struct before the tree is destroyed?

Of course, we would be happy with any information that would be
sufficient to deduce this gap, like the best lower bound (for a
minimization problem).

Thank you very much,

Nathann Cohen

[1] http://www.sagemath.org/
[2] http://lists.gnu.org/archive/html/help-glpk/2011-07/msg00068.html