/***********************************************************************
Xpress Optimizer Examples
=========================
file savesol.c
```````````````
Show how to save a postsolved solution to memory and access the
results of a global search. The program demonstrates the use of the
integer solution callback.
We take the knapsack problem in burglar.mat and instigate a global
search. Whenever an integer solution it found it is postsolved,
stored in memory, and printed to an output file. The best and final
solution values, and other global search information, are displayed
on screen. A log file is also created.
(c) 2017 Fair Isaac Corporation
***********************************************************************/
#include
#include
#include "xprs.h" /* Optimizer header file */
XPRSprob probg;
void XPRS_CC printsol(XPRSprob,void* data);
void XPRS_CC optimizermsg(XPRSprob prob,void* data,const char *sMsg,int nLen,int nMsgLvl);
void errormsg(const char *sSubName,int nLineNo,int nErrCode);
FILE *pOutput; /* Pointer to the output file */
int gnCol; /* Number of columns in the problem matrix */
double *gpIntSol; /* Integer solution values */
main()
{
int nReturn; /* Return value of Optimizer subroutine */
int nOptimizerVersion; /* Optimizer version number */
char sProblem[]="..\\data\\burglar";/* Problem name */
char sOutFile[]="savesol.out"; /* Output file name */
char sLogFile[]="savesol.log"; /* Log file name */
int nExpiry;
int nSol; /* Number of integer solutions found */
double dBestObj; /* Best objective value found */
int nNodes; /* Number of nodes solved in the global search */
int nActNodes; /* Number of active nodes ignored by the search */
int nLastNode; /* Node at which the last integer solution was found */
double dBestBnd; /* Best bound found in the global search */
int nGlStatus; /* Global search status - complete, incomplete, etc */
int i; /* Loop counter*/
char banner[256];
/* Delete and open output file */
remove(sOutFile);
pOutput=fopen(sOutFile,"w");
/* Initialise Optimizer */
nReturn=XPRSinit(NULL);
XPRSgetbanner(banner); printf("%s",banner);
if (nReturn == 8) return(1);
nReturn=XPRScreateprob(&probg);
if (nReturn != 0 && nReturn != 32) errormsg("XPRScreateprob",__LINE__,nReturn);
/* Tell Optimizer to call optimizermsg whenever a message is output */
nReturn=XPRSsetcbmessage(probg,optimizermsg,NULL);
/* Get and display the Optimizer version number */
if (nReturn=XPRSgetintcontrol(probg,XPRS_VERSION,&nOptimizerVersion))
errormsg("XPRSgetintcontrol",__LINE__,nReturn);
printf("Xpress Optimiser Subroutine Library Release %.2f\n\n",
(float)nOptimizerVersion/100);
/* Alow no cuts - so the problem does not solve too quickly */
if (nReturn=XPRSsetintcontrol(probg,XPRS_CUTSTRATEGY,0))
errormsg("XPRSsetintcontrol",__LINE__,nReturn);
/* Read the problem file */
if (nReturn=XPRSreadprob(probg,sProblem,"")) errormsg("XPRSreadprob",__LINE__,nReturn);
/*** Tell Optimizer to postsolve every integer solution found, save it to memory and
print the solution values to the output file ***/
/* Obtain postsolved solutions from memory */
if (nReturn=XPRSsetintcontrol(probg,XPRS_SOLUTIONFILE,0))
errormsg("XPRSsetintcontrol",__LINE__,nReturn);
/* Call function printsol whenever an integer solution is found */
nReturn=XPRSsetcbintsol(probg,printsol,NULL);
/* Get the number of columns and allocate space for the solution array */
if (nReturn=XPRSgetintattrib(probg,XPRS_COLS,&gnCol))
errormsg("XPRSgetintattrib",__LINE__,nReturn);
gpIntSol=malloc(gnCol*sizeof(double));
if (!gpIntSol) errormsg("malloc",__LINE__,-1);
/*** Search for integer solutions ***/
printf("Solving problem %s:\n\n",sProblem);
fprintf(pOutput,"Solving problem %s:\n\n",sProblem);
if (nReturn=XPRSmaxim(probg,"g")) errormsg("XPRSmaxim",__LINE__,nReturn);
/*** Retrieve the results of the global search ***/
/* Get the number of integer solutions found */
if (nReturn=XPRSgetintattrib(probg,XPRS_MIPSOLS,&nSol))
errormsg("XPRSgetintattrib",__LINE__,nReturn);
/* Get the objective value of the best integer solution found */
if (nReturn=XPRSgetdblattrib(probg,XPRS_MIPOBJVAL,&dBestObj))
errormsg("XPRSgetdblattrib",__LINE__,nReturn);
/* Get the number of outstanding nodes */
if (nReturn=XPRSgetintattrib(probg,XPRS_ACTIVENODES,&nActNodes))
errormsg("XPRSgetintattrib",__LINE__,nReturn);
/* Get the node at which the last feasible integer solution was found */
if (nReturn=XPRSgetintattrib(probg,XPRS_MIPSOLNODE,&nLastNode))
errormsg("XPRSgetintattrib",__LINE__,nReturn);
/* Get the number of nodes solved */
if (nReturn=XPRSgetintattrib(probg,XPRS_NODES,&nNodes))
errormsg("XPRSgetintattrib",__LINE__,nReturn);
/* Get the value of the best bound */
if (nReturn=XPRSgetdblattrib(probg,XPRS_BESTBOUND,&dBestBnd))
errormsg("XPRSgetdblattrib",__LINE__,nReturn);
/* Get the global status */
if (nReturn=XPRSgetintattrib(probg,XPRS_MIPSTATUS,&nGlStatus))
errormsg("XPRSgetintattrib",__LINE__,nReturn);
/*** Display the results of the global search ***/
switch (nGlStatus) {
case 3:
printf("Global search incomplete\n\n");
printf(" No integer solution found\n");
printf(" %d nodes searched\n",nNodes);
printf(" %d nodes remaining in search\n",nActNodes);
printf(" Best bound %g\n\n",dBestBnd);
break;
case 4:
printf("Global search incomplete\n\n");
printf(" %d integer solution%s found\n",nSol,(nSol==1) ? "" : "s");
printf(" %d nodes searched\n",nNodes);
printf(" %d nodes remaining in search\n",nActNodes);
printf(" Best bound %g\n\n",dBestBnd);
printf(" Best integer solution at node %d\n\n",nLastNode);
printf(" Objective value %g\n\n",dBestObj);
printf(" Solution values\n");
for (i=0; i |
