[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Help-glpk] Number of iterations in a single simplex iteration
From: |
Heinrich Schuchardt |
Subject: |
Re: [Help-glpk] Number of iterations in a single simplex iteration |
Date: |
Tue, 15 Nov 2016 07:51:13 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.4.0 |
Hello Umair,
in GNU Octave you have to set
param.msglev = 2
or
param.msglev = 3
to see the iteration count. See
https://www.gnu.org/software/octave/doc/v4.0.0/Linear-Programming.html
The different constants of the GLPK library like GLP_MSG_ON mentioned in
the Octave online help are documented in doc/glpk.pdf of the GLPK source.
Here is an example:
# provide normal GLPK ouput
param.msglev = 2;
# set up the problem
c = [1; -2; -3; -1];
a = [1, -1, -2, -1; 2, 0, 1, -4; -2, 1, 0, 1];
b = [4; 2; 1];
lb = [];
ub = [];
vartype = "CCCC";
ctype = "UUU";
s = -1;
# solve the problem
[xopt, fopt, status] = ...
glpk (c, a, b, lb, ub, ctype, vartype, s, param)
The output for the example looks like this:
* 0: obj = 0.000000000e+00 infeas = 0.000e+00 (0)
* 2: obj = 4.000000000e+00 infeas = 0.000e+00 (0)
2 is the number of iterations.
Best regards
Heinrich Schuchardt
On 11/15/2016 06:48 AM, Muhammad Arif, Umair wrote:
> Hi Heinrich
>
> Thanks for getting back to me. I am using the glpk library in octave. It
> has a glpk() function with some input parameters as mentioned in the
> below link:
>
> https://www.gnu.org/software/octave/doc/v4.0.0/Linear-Programming.html
>
> So my question was in this context. Can you help?
>
> Thanks
>
>
> On Nov 10, 2016 11:49 PM, "Heinrich Schuchardt" <address@hidden
> <mailto:address@hidden>> wrote:
>
> Hello Umair,
>
> the GLPK library sends the number of iterations to the terminal output.
>
> The simplex method output syntax is fully explained in the "Terminal
> output" subsection of the glp_simplex call documentation in doc/glpk.pdf
> (for GLPK 4.60 this is section 2.8.1) of the source distribution
> available at
> http://ftp.gnu.org/gnu/glpk/glpk-4.60.tar.gz
> <http://ftp.gnu.org/gnu/glpk/glpk-4.60.tar.gz>
>
> There is no glpk() function in the GLPK library. If you are using a
> wrapper to the GLPK library, see the documention there to find out how
> to enable terminal output.
>
> Best regards
>
> Heinrich Schuchardt
>
> On 11/10/2016 08:49 PM, Muhammad Arif, Umair wrote:
> > Hi there,
> >
> > Hope you are doing fine. I am using GLPK for solving the LP of my
> > research problem. I have to compare the number of iterations of
> simplex
> > method with the algorithm that I developed. So, is it possible to get
> > the number of simplex iterations performed when we call glpk()
> function
> > once.
> >
> > I know there is a parameter where we can set the maximum limit of
> > iterations but it does not specify how many iterations are
> performed in
> > a single glpk() call.
> >
> > Hope to receive a prompt response. Thanks
> >
> > Best Regards,
> >
> > *Umair M. Arif*
>