Re: [Bug-glpk] [Fwd: Re: [Fwd: Bus error for MIP solver / Simplex solver]]

[glpk xypron]

Hello Tony,

your mail had to be forwarded manually because your are not member of the 
mailing list. See
https://lists.gnu.org/mailman/listinfo/bug-glpk
https://lists.gnu.org/mailman/listinfo/help-glpk

Problems using GLPK should be addressed to the help list, not to the bug list.

The problem in your code is that you do not allocate memory for variable parm.

You can either use malloc for allocating memory (do not forget to free the 
memory after usage) or you could use a local variable which is not a pointer 
like:

glp_iocp parm;
glp_init_iocp(&parm);
parm.presolve = GLP_ON;
parm.binarize = GLP_ON;
glp_intopt(mip, &parm);

Best regards

Xypron


> -------- Forwarded Message --------
> Subject: Re: [Bug-glpk] [Fwd: Bus error for MIP solver / Simplex solver]
> Date: Mon, 7 May 2012 15:21:07 +0200
> 
> Hi,
> 
> I tested your code, and it works perfectly. I don't see the issue with
> my code though. Is it somehow a problem with passing a parameter? 
> 
> Here is my code:
> 
> /* glpktest.c */
> 
> #include <stdio.h>
> #include <stdlib.h>
> #include <glpk.h>
> 
> int main() {
> 
> 
>     glp_prob *mip;
>     glp_tran *tran;
>     glp_iocp *parm;
>     int ret;
>     mip = glp_create_prob();
> 
> //1.allocating workspace
>     tran = glp_mpl_alloc_wksp(); 
> //2.reading  model section
>     ret = glp_mpl_read_model(tran, "sudoku.mod", 1);
>     if (ret != 0) { 
>     printf("Error on translating model\n");
>     goto skip;
>     }
> // 3.reading data section
>     ret = glp_mpl_read_data(tran, "sudoku.dat");
>     if (ret != 0) { 
>     printf("Error on translating data\n");
>     goto skip;
>     }
> //4.generating model
>     ret = glp_mpl_generate(tran, NULL);
>     if (ret != 0) { 
>     printf("Error on generating model\n");
>     goto skip;
>     }
> //5.building the problem object
>     glp_mpl_build_prob(tran, mip);
> //6.solving the problem
>     //With parm, no need to call the simplex
>     //glp_simplex(mip, NULL);
>     
>     glp_init_iocp(parm); 
>     parm->presolve = GLP_ON; 
>     parm->binarize = GLP_ON; 
>     glp_intopt(mip, parm);
>     // ret =glp_print_mip(mip, "out.txt");
>     // if (ret != 0) { 
>     //     cerr << "Error on writing the solution" << endl;
>     //     goto skip;
>     // }
> //7.postsolving the problem
>     ret = glp_mpl_postsolve(tran, mip, GLP_MIP);
>     if (ret != 0)
>     printf("Error on postsolving model\n");
> //8.freeing the workspace
> skip: glp_mpl_free_wksp(tran);
>     glp_delete_prob(mip);
>     return 0;
> 
> }
> 
> /* eof */
> 
> If I use just the simplex method, the result is not good. 
> 
> As I said before, the java implementation is exactly the same, and it
> works though.
> 
> 
> 
> 
> 2012/5/5 Andrew Makhorin <address@hidden>
>         Hello,
>         
>         > Well, as nobody is able to find any solution, I tried couple
>         of
>         > things, unsuccessfully. However, I have run the program once
>         again
>         > with gdb to see where was the problem exactly, to dig a bit
>         and to
>         > maybe figure out the problem. Once again, unsuccessfully. I
>         copy/paste
>         > the debugger output here:
>         >
>         > #0  0x00007ffff7486edc in getenv ()
>         > from /lib/x86_64-linux-gnu/libc.so.6
>         > #1  0x00007ffff74eca9e in ?? ()
>         from /lib/x86_64-linux-gnu/libc.so.6
>         > #2  0x00007ffff74ecf52 in ?? ()
>         from /lib/x86_64-linux-gnu/libc.so.6
>         > #3  0x00007ffff7b22b8c in glp_time () at glpenv06.c:60
>         > #4  0x00007ffff7b86c17 in init_csa (lp=<optimized out>,
>         csa=<optimized
>         > out>)
>         >     at glpspx01.c:392
>         > #5  _glp_spx_primal (lp=<optimized out>, parm=<optimized out>)
>         >     at glpspx01.c:2590
>         > #6  0x00007ffff7b0163b in glp_simplex (P=0x6aec20,
>         > parm=0x7fffffffe0a0)
>         >     at glpapi06.c:452
>         > #7  0x00007ffff7b04a96 in preprocess_and_solve_mip
>         > (parm=0x7fffffffe4f0,
>         >     P=0x604500) at glpapi09.c:371
>         > #8  glp_intopt (P=0x604500, parm=0x7fffffffe4f0) at
>         glpapi09.c:593
>         > #9  0x0000000000400c69 in main () at glpk.cpp:44
>         >
>         > at line 44, I have the following:
>         >
>         > glp_intopt(mip, parm);
>         >
>         > I have implemented a Java version of this program (linked to
>         the java
>         > libglpk) and it is an exact copy of the C++ code. Weird thing
>         is it
>         > works perfectly (I used the stand alone glpsol to check).
>         >
>         > It somehow solve my problem for this case, but it would be
>         good to
>         > know what is the issue with the c++ lib.
>         
>         
>         I calculate that this bug is not related to glpk. According to
>         the
>         traceback you provided the exception occured in getenv which is
>         called
>         indirectly from glp_time. Since glp_time calls only two libc
>         functions
>         gettimeofday and gmtime, there is something wrong in the
>         environment.
>         
>         I'd suggest you to run an equivalent of the following program:
>         
>         /* glpsol.c */
>         
>         #include <glpk.h>
>         
>         int main(int argc, const char *argv[])
>         {     /* stand-alone LP/MIP solver */
>              return glp_main(argc, argv);
>         }
>         
>         /* eof */
>         
>         in the standard C environment you are using. If it works, please
>         find
>         the bug in your code. Thanks.
>         
>         
>         Andrew Makhorin
>         
> 
> 
> 
> -- 
> Tony Khosravi Dehkourdi
> 
> MSc. Student - Computer Systems
> Linköping University
> Elève ingénieur -- Génie Informatique, Systèmes et Réseaux
> d'Informations (GI06)
> Université de Technologie de Compiègne
> Tel:+46 7 60 69 51 57
> 
> 
> _______________________________________________
> Bug-glpk mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/bug-glpk

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