Re: GLPK Exact option not working

[Andrew Makhorin]

Hi Prabhu,

Thank you for your interest in glpk.


I used the following commands to build glpk 5.0:

./configure --with-gmp

make

cd examples

./glpsol --mps ./murtagh.mps --max --exact

and all works correctly:

GLPSOL--GLPK LP/MIP Solver 5.0
Parameter(s) specified in the command line:
 --mps ./murtagh.mps --max --exact
Reading problem data from './murtagh.mps'...
Problem: OILREFI
Objective: PROFIT
74 rows, 81 columns, 504 non-zeros
600 records were read
One free row was removed
glp_exact: 73 rows, 81 columns, 474 non-zeros
GNU MP bignum library is being used
*     0:   objval =                      0   (42)
*   103:   objval =       126.057124110517   (0)
OPTIMAL SOLUTION FOUND
Time used:   0.1 secs
Memory used: 0.1 Mb (114012 bytes)

Please check if the GNU MP library is correctly installed.
If so, after running the configure script check the file
config.h created by the script and make sure that using the 
GMP library is enabled:

#define HAVE_GMP 1
/* defined if the GNU MP bignum library is available */
/* requires <gmp.h> and -lgmp */


Best regards,

Andrew Makhorin


PS: Please report bugs to <bug-glpk@gnu.org>. Thanks.




On Sat, 2022-09-17 at 12:29 +0930, Prabhu Manyem wrote:
> Dear Andrew,
> 
> The "exact" option in my GLPK 5.0 (command line) is failing.. It says
> "GLPK bignum module is being used (Consider installing GNU MP to
> attain a much better performance.)"
> 
> However, I have installed GMP, and the GLPK 5.0 compilation and
> installation have also used GMP... Strange!
> 
> Let me attach my installation config file.. I copied the original
> config file into a new file called config-log.txt.
> 
> My configure command:
>      ./configure --with-gmp --enable-dl=ltdl
> 
> Some lines about GMP in the config file:
> configure:8316: checking gmp.h usability
> configure:8316: gcc -c -g -O2  conftest.c >&5
> configure:8316: $? = 0
> configure:8316: result: yes
> configure:8316: checking gmp.h presence
> configure:8316: gcc -E  conftest.c
> configure:8316: $? = 0
> configure:8316: result: yes
> configure:8316: checking for gmp.h
> configure:8316: result: yes
> configure:8326: checking whether to use GNU MP bignum library
> configure:8329: result: yes
> :
> ac_cv_header_gmp_h=yes
> :
> LIBS='-lltdl -lgmp -lm '
> 
> I downloaded and installed gmp-6.2.1, and then, I installed GLPK
> again.
> 
> LTDL has also been installed... Let me also attach the results of my
> "locate gmp" command in my Linux machine.
> 
> Any idea why the GLPK (at the command line) is unable to recognise
> GMP?  Thank you very much!
> 
> -Prabhu
> 
> Dr Prabhu Manyem
> Retired Professor of Applied Mathematics
> Nanchang Institute of Technology