[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Help-glpk] How to tell if lpx_simplex() needs to be restarted?
From: |
leowl |
Subject: |
[Help-glpk] How to tell if lpx_simplex() needs to be restarted? |
Date: |
Mon, 10 Apr 2006 06:27:50 +0800 |
Thanks to all, especially to Andrew, that I am able to get glpk up and running.
For the small to medium-sized data sets, the lpx_simplex(lp) solution pops out
pretty
quickly and there is no problem. I do, however, have some questions when the
data sets get
large.
For a really large data set (ne=160,000 and ia with some 200,000 elements),
after 7 hours,
the DOS screen reads:
.
.
257000: objval = 0.000000000e+000 infeas = 1.000000000e+000 (0)
.
.
and it has been like that for a while and continues to be so. Does this mean I
have done
something wrong? Or is the process still running and I should give it more time?
And on another (smaller) set of data, after 9 hours, the DOS screen reads:
.
.
850684: objval 5.138313894e+000 infeas = 4.854494849e-004 (8)
spx_simplex: numerical instability (primal simplex, phase II)
850684: objval 5.138313894e+000 infeas = 1.000000000e+000 (8)
850800: objval 5.138297412e+000 infeas = 5.798016607e-001 (8)
.
.
.
and the process continues. sometimes, I get a spx_simplex: numerical
instability (primal
simplex, phase I) message too.
9+ hours of simulation seems far too long, compared to the minutes taken for
the smaller
data sets. In general, how do I know if I have done something wrong and I
should
debug/restart the process? And how can I tell if everything is going on fine
and I should
just let the computer do its work?
Thanks in advance!
//-------------------
I run my simulations on a Pentium 1.5Ghz with 512MB RAM. This is how my code
looks:
/*for loop that assigns values to ne, ia, ja, ar here*/
lpx_load_matrix(lp, ne, ia, ja, ar);
lpx_simplex(lp);
Z = lpx_get_obj_val(lp);
--
This message was sent on behalf of address@hidden at openSubscriber.com
http://www.opensubscriber.com/messages/address@hidden/topic.html
- [Help-glpk] How to tell if lpx_simplex() needs to be restarted?,
leowl <=
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/10
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, Andrew Makhorin, 2006/04/10
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, Andrew Makhorin, 2006/04/10
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11
- Re: [Help-glpk] How to tell if lpx_simplex() needs to be restarted?, leowl, 2006/04/11