Re: [Help-glpk] Number of iterations in a single simplex iteration

[Heinrich Schuchardt]

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*
>