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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=DE link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><b><span style='color:windowtext;mso-fareast-language:DE'>Von:</span></b><span style='color:windowtext;mso-fareast-language:DE'> Gregor Hendel [mailto:hendel@zib.de] <br><b>Gesendet:</b> Dienstag, 18. Juni 2019 10:38<br><b>An:</b> Büsing, Henrik <h.buesing@fz-juelich.de>; scip@zib.de<br><b>Betreff:</b> Re: [SCIP] MPS Read and Write and Structure Detection<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Good morning Henrik,<br><br>may I introduce you to <a href="https://scip.zib.de/doc/html/group__PublicSolutionMethods.php#ga3bd6c0f66c0179c77cf4c708ee2bef45">SCIPprintSol()</a>, a reliable little helper in such situations.<span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><b><i><span lang=EN-US style='color:#1F497D'>[Büsing, Henrik] Great! Thank you!</span></i></b><span lang=EN-US><br><br>The SCIP documentation is in general a good place to search for information. </span>You should make yourself familiar with the <a href="https://scip.zib.de/doc/html/group__PublicSolutionMethods.php">methods available</a> for the SCIP_SOL* structure.<br><br>Happy printing,<br>Gregor<span style='font-size:12.0pt;mso-fareast-language:DE'><o:p></o:p></span></p><div><p class=MsoNormal>Am 18.06.19 um 09:12 schrieb "Büsing, Henrik":<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><span style='color:#1F497D'>Dear Gregor, </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Thank you for your answer! I am still unsure how to display the solution correctly. I am using the code [1], but this only gives the first value of the solution three times. </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Regarding what we would like to do: Our aim is to use hardware with distributed memory to solve LPs and MIPs. I have problems in MPS-format and would like to detect a block-structure automatically to solve the different blocks in parallel. </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><br>Best, <br>Henrik</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>[1]</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> SCIP_VAR** vars;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> vars = SCIPgetVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> SCIP_SOL* sol;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> sol = SCIPgetBestSol(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> for (int i=0; i<3; ++i)</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> {</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> cout << "Solution: " << SCIPgetSolVal(scip, sol, vars[i]) << endl;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> }</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'> </span><o:p></o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='color:windowtext;mso-fareast-language:DE'>Von:</span></b><span style='color:windowtext;mso-fareast-language:DE'> Scip [<a href="mailto:scip-bounces@zib.de">mailto:scip-bounces@zib.de</a>] <b>Im Auftrag von </b>Gregor Hendel<br><b>Gesendet:</b> Montag, 17. Juni 2019 12:44<br><b>An:</b> <a href="mailto:scip@zib.de">scip@zib.de</a><br><b>Betreff:</b> Re: [SCIP] MPS Read and Write and Structure Detection</span><o:p></o:p></p></div></div><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Hi Henrik,<br><br>the queens example (introd)uses a data structure "QueensSolver" that stores variables in a 2D array, which is a very intuitive representation of an n-by-n checkers board. Make sure you read the comments when you start working with an example (queens.hpp):<o:p></o:p></p><pre> /** @brief one binary variable for each field (i,j) on the chess bord<o:p></o:p></pre><pre> *<o:p></o:p></pre><pre> * To access variable information (objective value, bounds,<o:p></o:p></pre><pre> * etc.) use the SCIP_VAR * pointer. Since we want to know the<o:p></o:p></pre><pre> * value of each variable in the solution, we have to store<o:p></o:p></pre><pre> * these pointers.<o:p></o:p></pre><pre> */<o:p></o:p></pre><pre> std::vector<std::vector<SCIP_VAR *> > _vars;<o:p></o:p></pre><p class=MsoNormal style='margin-bottom:12.0pt'><br>The result of SCIPgetVars() is a 1D-Array, which you should indeed **not** access by a 2D-index.<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US>Regarding your question about detection: The mps-format does not preserve decomposition label information. </span>A detected arrowhead structure will be lost. SCIP in its current version does not support reading decompositions.<br>It would be good if you could elaborate a little bit more on what you are trying to achieve, so that the SCIP and GCG team can give you a better suggestion how to pursue that.<br><br>Cheers,<br>Gregor<br><br><br><br><o:p></o:p></p><div><p class=MsoNormal>Am 17.06.19 um 11:01 schrieb "Büsing, Henrik":<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>Dear SCIP users, <o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span lang=EN-US>I would like to read in an MPS-file, detect a possible arrowhead structure via dec_hcgpartition.cpp and then write the MPS-file with the new structure. I was able to read in an MPS-file and solve it, but I get a segmentation fault while writing the MPS-file (see [2] for the code). When running in debugger I get error [1].</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Could you point out what I am doing wrong while trying to write the MPS-file? <br>Additionally, why is vars two-dimensional? Should this not be just a long array with all the variables in it? How do I print the solution in a correct way? A nested loop over i and j does not honor the sparse structure of the constraint matrix A. </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Finally, is there an example on how to use the structure detection of GCG? </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Thank you very much for your help! <br><br>Best, <br>Henrik</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>[1]</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Program received signal SIGSEGV, Segmentation fault.</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>SCIPreaderGetData (reader=reader@entry=0x0)</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> at /home/henrik/Code/scipoptsuite-6.0.1/scip/src/scip/reader.c:488</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>488 return reader->readerdata;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>[2]</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>// Derived from Queens example by Cornelius Schwarz</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>#include <scip/scip.h></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>#include <scip/scipdefplugins.h></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>#include "scip_exception.hpp"</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>#include <iostream></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>using namespace std;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>/** main function **/</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>int</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>main()</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>{</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // Define scip pointer and filename</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP* scip;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_READER* reader;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> const char* filename="/home/henrik/JSC/FINE_exampleMpsFiles/toy.MPS";</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> cout << filename << endl;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_RESULT* result;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> result = new SCIP_RESULT[3];</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // Create scip environment</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_CALL_EXC(SCIPcreate(& scip));</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // Load desired plugins</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_CALL_EXC(SCIPincludeDefaultPlugins(scip));</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // disable scip output to stdout</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIPmessagehdlrSetQuiet(SCIPgetMessagehdlr(scip), TRUE);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // Read in *.MPS file</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIPreadMps(scip, reader, filename, result, </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span>NULL,NULL,<o:p></o:p></p><p class=MsoNormal> NULL,NULL, <o:p></o:p></p><p class=MsoNormal> NULL,NULL<o:p></o:p></p><p class=MsoNormal> <span lang=EN-US>);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // Solve</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_CALL_EXC(SCIPsolve(scip));</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> // Display solution</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_VAR** vars;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> vars = SCIPgetVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_SOL* sol;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> sol = SCIPgetBestSol(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> for (int i=0; i<3; ++i)</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> for (int j=0; j<3; ++j)</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> {</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> cout << "Solution: " << SCIPgetSolVal(scip, sol, &vars[i][j]) << endl;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> }</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int nvars = SCIPgetNVars(scip); </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int nbinvars = SCIPgetNBinVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int nintvars = SCIPgetNIntVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int nimplvars = SCIPgetNImplVars(scip); </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int ncontvars = SCIPgetNContVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_Real objscale = 1.0;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_Real objoffset = 0.0;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_VAR** fixedvars = SCIPgetFixedVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int nfixedvars = SCIPgetNFixedVars(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIP_CONS** conss = SCIPgetConss(scip);</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> int nconss = SCIPgetNConss(scip); </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> const char* name="Toy"; </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> SCIPwriteMps(scip, reader, NULL, name, FALSE, SCIP_OBJSENSE_MINIMIZE,</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> objscale, objoffset, vars, nvars, nbinvars, nintvars,</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> nimplvars, ncontvars, fixedvars, nfixedvars, conss,</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> nconss, result</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> );</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> return EXIT_SUCCESS;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>}</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>-- </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Dipl.-Math. Henrik Büsing</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Jülich Supercomputing Centre</span><o:p></o:p></p><p class=MsoNormal>Institute for Advanced Simulation<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>Forschungszentrum Jülich<o:p></o:p></p><p class=MsoNormal>Wilhelm-Johnen-Straße<o:p></o:p></p><p class=MsoNormal><span lang=EN-US>52425 Jülich, Germany</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Phone: +49-2461-61-9884</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Fax: +49-2461-61-6656</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>E-Mail: <a href="mailto:H.Buesing@fz-juelich.de">H.Buesing@fz-juelich.de</a></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>WWW: <a href="http://www.fz-juelich.de/ias/jsc">http://www.fz-juelich.de/ias/jsc</a></span><o:p></o:p></p><p class=MsoNormal>-------------------------------------------------------------------------------------<o:p></o:p></p><p class=MsoNormal>-------------------------------------------------------------------------------------<o:p></o:p></p><p class=MsoNormal>Forschungszentrum Juelich GmbH<o:p></o:p></p><p class=MsoNormal>52425 Juelich<o:p></o:p></p><p class=MsoNormal>Sitz der Gesellschaft: Juelich<o:p></o:p></p><p class=MsoNormal>Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. 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