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Re: [Bug-glpk] [Fwd: MIP solver bug]


From: Chris Matrakidis
Subject: Re: [Bug-glpk] [Fwd: MIP solver bug]
Date: Thu, 12 Jan 2017 15:20:49 +0200

Hi Emma,

> In this case, the default branching works better than pseudocost branching.
> However, in general the original problem is much slower than the previous one 
> (lp_modified.txt by removing x[0.0])

In general, pseudocost branching is considered more accurate, but
needs more time for initialisation. However there is no guarantee that
this holds for any problem.

Moreover, I see that your problem is not very well scaled (although a
lot better than with big M):
 A: min|aij| = 1.307e-009  max|aij| = 7.569e+005  ratio = 5.792e+014

Can you change the formulation to reduce the range of values in the constraints?

Best Regards,

Chris Matrakidis



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