Re: [Help-glpk] Patches to improve pseudocost initialisatiion speed

[Andrew Makhorin]

Hi Chris,

Thank you very much for your great help.

I'm starting to make changes according to some of your patches. I think
it will take a time, in particular, because the dual simplex driver
routine should be revised, rewritten, and tested more carefully.


Best regards,

Andrew Makhorin


On Sun, 2017-01-08 at 17:59 +0200, Chris Matrakidis wrote:
> Andrew,
> 
> Since you are preparing a new GLPK release, I'm sending you three
> patches to consider, that improve the speed of pseudocost
> initialization.
> The first reuses the same glp_prob in each round to avoid unnecessary
> copying, the second introduces a bfd_copy function and the third uses
> bfd_copy to avoid recalculating the exact same factorisation in every
> simplex call during each initialisation round.
> These patches do not affect the execution order of the code, only the
> initialisation speed: in all tests I did, I get the exact same number
> of nodes and simplex iterations
> 
> Best Regards,
> 
> Chris Matrakidis