[Help-glpk] Questions regarding Simplex during Integer Optimization

[Sebastian Heger]

Hey community,

I want to set overall simplex parameters for an integer (linear) optimization. 
I am little bit confused, that I “only” can use glp_simplex (where I can set 
parameters like pricing, meth, etc.) prior to the integer optimization. But 
then the MILP has no presolve option and I seems that the simplex with standard 
settings (as far as I can interpret the code/output) is applied during 
branch-and-cut. The documentation doesn’t tell me more details about that.

So, I thought to ask community for some explanation. Did it get the situation 
right and might there be future enhancements? I am not a native c developer, 
but after I inspected the code a little bit, it might be possible to pass a 
smcp optionally also to integer optimization or make parts of the parameters 
(at least meth, pricing) to be available through iocp. I could imagine an 
overall performance jump if dual simplex can be fully used during integer 
optimization for a variety of models.

Thanks for your support.

Sebastian Heger
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Re: [Help-glpk] Thread Safety of GLPK

[Andrew Makhorin]

> In the GLPK documentation, paragraph "2.1.3 Thread Safety" states:
> 
> 
> "The standard version of GLPK API is not thread safe and therefore
> should not be used in multi-threaded programs.”

The *standard* (i.e. ANSI C89) version is not thread safe. However,
starting from 4.61 (released on Jan 2017) glpk can be used in
multi-threaded programs on some platforms (including GNU/Linux and MS
Windows); for more details please see:
https://lists.gnu.org/archive/html/help-glpk/2017-01/msg00111.html .
(It's better to use the most recent version, which is 4.63.)




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