[Help-glpk] warm start with glpk

[Richard Simonnet]

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.)
>> 
>> 
>