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[Help-glpk] warm start with glpk
From: |
Richard Simonnet |
Subject: |
[Help-glpk] warm start with glpk |
Date: |
Fri, 16 Jul 2010 16:06:29 +0200 |
Hello,
I'm a PhD Student and I'm using glpk to solve quite large linear programming
problems.
I want to notice that I'm french and I apologize if my english is bad, I'll try
to explain clearly my problem.
At first I want to thank you and all the team ; I'm using glpk since release
4.13, and I'm very satisfied with this package which helps me a lot in my work !
Now I'm using glpk 4.43, I've read the doc and I don't find how to make a "warm
start" :
I want to solve a first time my problem, and then I would like to modify only
one item ( an objective coefficient or a bound value ), and solving again the
problem in "warm start", I mean by using the basis previously found on first
solving without solving problem again or factorisation again ( just in order to
save time, my problems are very long to solve and I will have to make many
iteration this way ).
I've found the routine lpx_warms_up which looks like but it's not exactly what
I need.
I've not found in the documentation the routines I need, is it possible to do
that with glpk ?
If it is, can you please highlight me with the routines I should use ?
Thanks and again thank you for your job with glpk !
Le 26 mars 2010 à 10:03, Richard Simonnet a écrit :
>
> It works fine again with glpk 4.43 strange ....
>
> thanks
>
> Le 18 mars 2010 а 12:15, Andrew Makhorin a йcrit :
>
>>> At first, I want to explain that I'm a french student and I
>>> apologize if my english is bad, and I'll try to explain clearly my
>>> problem.
>>
>>> As part of my PhD, I'm using the glpk routines to solve linear
>>> programming problems, with programs in language C running under Linux
>>> terminal.
>>
>>> I was using glpk 4.25 and I've just updated to glpk 4.35 and with
>>> this release, the function "glp_term_out" with the option "GLP_OFF"
>>> seems to not work.
>>
>>> While running program with this option, I get no error message but
>>> the program seems to be in "pause" on this step; though I was using
>>> this option with glpk 4.25 without problem.
>>
>>> Is there a known problem with this function ?
>>
>> Hmm... Glp_term_out must work. If you disable the terminal output and
>> then call glp_simplex, it may happen that the simplex solver is stalling
>> due to degeneracy, however, you cannot see that. Try to enable the
>> terminal output to make sure that glp_simplex is not stalling.
>>
>> (Please note that the most recent version of glpk is 4.43.)
>>
>>
>
- [Help-glpk] warm start with glpk,
Richard Simonnet <=