[Scip] error message on calling SCIPwriteLP
Stefan Vigerske
stefan at math.hu-berlin.de
Tue Oct 1 18:11:08 CEST 2013
Hi,
try to add the constraints to your problem, too:
SCIP_CALL( SCIPaddCons(scip, cons[i]) );
(or something similar).
Stefan
On 10/01/2013 05:33 PM, Shahin Gelareh wrote:
> Dear Gregor
>
> Thank you for your email.
> That works.
>
> However, what I still do not understand and still challenging with is the
> following:
>
>
> std::vector<SCIP_CONS*> cons(3);
>> for(int i = 0; i < 3; i++)
>> {
>> string name = "const[" + itos(i) + "]";
>> SCIP_CALL(SCIPcreateConsLinear(scip, &cons[i], (const
>> char*)name.c_str(), 0.0,
>> NULL, NULL, 0, 3+i,
>> TRUE, TRUE, TRUE, TRUE, TRUE,
>> FALSE, FALSE, FALSE, FALSE, FALSE
>> ));
>>
>> }
>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[0], var[0], 2));
>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[0], var[1], 3));
>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[0], var[2], 4));
>>
>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[1], var[0], 3));
>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[1], var[1], 4));
>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[1], var[2], 5));
>>
>
> None of the " SCIP_CALL(SCIPaddCoefLinear ( ..." has an affect on the
> constraints and the generated LP file turn out to be:
> \ SCIP STATISTICS
> \ Problem name : triKnapsack
> \ Variables : 3 (3 binary, 0 integer, 0 implicit integer, 0
> continuous)
> \ Constraints : 0
> \ Obj. scale : 1
> \ Obj. offset : 0
> Maximize
> Obj: +1 x[0] +2 x[1] +3 x[2]
> Subject to
> Bounds
> 0 <= x[0] <= 1
> 0 <= x[1] <= 1
> 0 <= x[2] <= 1
> Binaries
> x[0] x[1] x[2]
> End
>
> regards,
> Shahin
>
>
>
>
>
>
>
>
> On Tue, Oct 1, 2013 at 4:26 PM, Gregor Hendel <hendel at zib.de> wrote:
>
>> Hi Shahin,
>>
>> I haven't run your code but I think there are two issues:
>> 1. In the commented part
>>
>> // FILE* f=fopen("tri", "w");
>> //SCIP_CALL(SCIPprintOrigProblem(scip,f, "lp", 0));
>>
>> there is no fclose(f), that's probably why you see no output from this
>> method (and the reason why you commented it out)
>>
>> 2. It is not possible to call SCIPwriteLP() at that point in time because
>> after SCIP has returned from SCIPsolve() you're not in the solving stage
>> anymore, and the LP data structure has already been cleared.
>>
>> I think you most likely want to use SCIPprintOrigProblem().
>>
>> Regards,
>> Gregor
>>
>>
>> Am 01.10.2013 15:20, schrieb Shahin Gelareh:
>>
>> The code is the following --very simple.
>>
>>> I use VS2010. The same result under Ubuntu.
>>>
>>
>>
>>> regards,
>>> Shahin
>>>
>>>
>>> /**@file triKnapsack.c
>>> * @brief The first example for solving a three-constraint knapsack
>>> problem
>>> * @author Shahin Gelareh
>>> *
>>> * This example shows how to setup and solve the model using SCIP as
>>> callable library.
>>> *
>>>
>>>
>>> /*--+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
>>>
>>> #include <stdio.h>
>>>
>>> //#include "scip/scip.h"
>>> //#include "scip/scipdefplugins.h"
>>> /* include SCIP components */
>>> #include "objscip/objscip.h"
>>> #include "objscip/objscipdefplugins.h"
>>>
>>> #include <iostream>
>>> #include <sstream>
>>> #include <string>
>>> #include <vector>
>>> using namespace scip;
>>> using namespace std;
>>>
>>> string itos(int arg) //converts an integer to a std::string
>>> {
>>> ostringstream buffer;
>>> buffer << arg;
>>> return buffer.str();
>>> }
>>>
>>>
>>> /** main method starting SCIP */
>>> int main(
>>> int argc, /**< number of arguments
>>> from the shell */
>>> char** argv /**< array of shell
>>> arguments */
>>> ) /*lint --e{715}*/
>>> {
>>> SCIP_RETCODE retcode;
>>> SCIP* scip; // create the null pointer to SCIP
>>> SCIP_CALL(SCIPcreate(&scip)); // initialize the SCIP instance
>>>
>>> SCIP_CALL(SCIPincludeDefaultPlugins(scip)); // load the default
>>> plugins
>>> // create an empty problem
>>> SCIP_CALL(SCIPcreateProb(scip, "triKnapsack", NULL, NULL, NULL,
>>> NULL, NULL, NULL, NULL
>>> ));
>>> SCIP_CALL(SCIPsetObjsense(scip, SCIP_OBJSENSE_MAXIMIZE));
>>>
>>> std::vector<SCIP_VAR*> var(3);
>>> for(int i = 0; i < 3; i++)
>>> {
>>> string name = "x[" + itos(i) + "]";
>>> SCIP_CALL(SCIPcreateVar(scip, &var[i], (const char*)name.c_str(),
>>> 0.0, 1.0, i+1, SCIP_VARTYPE_BINARY,
>>> TRUE, FALSE, NULL,
>>> NULL, NULL, NULL, NULL));
>>> SCIP_CALL(SCIPaddVar(scip, var[i]));
>>> }
>>> std::vector<SCIP_CONS*> cons(3);
>>> for(int i = 0; i < 3; i++)
>>> {
>>> string name = "const[" + itos(i) + "]";
>>> SCIP_CALL(SCIPcreateConsLinear(scip, &cons[i], (const
>>> char*)name.c_str(), 0.0,
>>> NULL, NULL, 0, 3+i,
>>> TRUE, TRUE, TRUE, TRUE, TRUE,
>>> FALSE, FALSE, FALSE, FALSE, FALSE
>>> ));
>>>
>>> }
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[0], var[0], 2));
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[0], var[1], 3));
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[0], var[2], 4));
>>>
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[1], var[0], 3));
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[1], var[1], 4));
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[1], var[2], 5));
>>>
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[2], var[0], 4));
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[2], var[1], 5));
>>> SCIP_CALL(SCIPaddCoefLinear(scip, cons[2], var[2], 6));
>>> // solve
>>> SCIP_CALL(SCIPsolve(scip));
>>> SCIP_CALL(SCIPwriteLP(scip, "triKP"));
>>> // FILE* f=fopen("tri", "w");
>>>
>>> //SCIP_CALL(SCIPprintOrigProblem(scip,f, "lp", 0));
>>>
>>>
>>>
>>> if( SCIPgetNSols(scip) > 0 )
>>> {
>>> SCIPinfoMessage(scip, NULL, "\nSolution:\n");
>>> SCIP_CALL( SCIPprintSol(scip, SCIPgetBestSol(scip), NULL, FALSE) );
>>> }
>>>
>>> SCIP_CALL( SCIPfree(&scip) );
>>>
>>> return SCIP_OKAY;
>>> }
>>>
>>>
>>>
>>> On Tue, Oct 1, 2013 at 2:03 PM, Ambros Gleixner <gleixner at zib.de> wrote:
>>>
>>>> Hello Shahin,
>>>>
>>>> you need to give us some more details. Can you compile SCIP in debug
>>>> mode (make OPT=dbg), run everything in a debugger, and send us the
>>>> backtrace?
>>>>
>>>> Also, how and where exactly do you call SCIPwriteLP()?
>>>>
>>>> Best regards,
>>>>
>>>> Ambros
>>>>
>>>>
>>>> Am 01.10.2013 13 <01.10.2013%2013>:41, schrieb Shahin Gelareh:
>>>>
>>>>> Dear SCIPers
>>>>>
>>>>> I build my model and it solves fine.
>>>>> I need to extract the LP model to verify my mode.
>>>>>
>>>>> When I call it for the first time I get no output and at the same time
>>>>> no error message.
>>>>> The next time I run the executable it crashes :(
>>>>>
>>>>> Anything I am missing here?
>>>>>
>>>>> Best
>>>>> Shahin
>>>>>
>>>>> --
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Scip mailing list
>>>>> Scip at zib.de
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>>>>>
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>>>
>>>
>>>
>>> --
>>>
>>>
>>>
>>
>>
>> --
>>
>>
>>
>>
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>
>
> --
>
>
>
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