/***********************************************************************
Xpress Optimizer Examples
=========================
file loadmipsol.c
````````````````
Implement a rounding type heuristic in the optnode callback
to demonstrate how to load solutions into the optimizer.
(c) 2017 Fair Isaac Corporation
***********************************************************************/
#include "stdlib.h"
#include "stdio.h"
#include "memory.h"
#include "math.h"
#include "xprs.h"
#if defined(WIN32) || defined(_WIN32)
#include "windows.h"
#else
#include "pthread.h"
#endif
/**********************************************************************************\
* Name: errormsg *
* Purpose: Display error information about failed subroutines. *
* Arguments: const char *sSubName Subroutine name *
* int nLineNo Line number *
* int nErrCode Error code *
* Return Value: None *
\**********************************************************************************/
void errormsg(XPRSprob probg, const char *sSubName,int nLineNo,int nErrCode)
{
int nErrNo = -1; /* Optimizer error number */
/* Append Optimizer error number, if available */
if(probg && nErrCode==32) {
XPRSgetintattrib(probg,XPRS_ERRORCODE,&nErrNo);
}
/* Print error message */
printf("ERROR:%s(%d):Failure in function '%s' : Return : %d : Error : %d\n", __FILE__, __LINE__, sSubName, nErrCode, nErrNo);
/* Free memory, close files and exit */
if(probg) XPRSdestroyprob(probg);
XPRSfree();
exit(nErrCode);
}
#define GetProb_XPRSchgbounds(a1,a2,a3,a4,a5) a1
#define GetProb_XPRScopycontrols(a1,a2) a1
#define GetProb_XPRScopyprob(a1,a2,a3) a1
#define GetProb_XPRScreateprob(a1) *(a1)
#define GetProb_XPRSgetbanner(a1) NULL
#define GetProb_XPRSgetdblattrib(a1,a2,a3) a1
#define GetProb_XPRSgetdblcontrol(a1,a2,a3) a1
#define GetProb_XPRSgetglobal(a1,a2,a3,a4,a5,a6,a7,a8,a9,a10) a1
#define GetProb_XPRSgetintattrib(a1,a2,a3) a1
#define GetProb_XPRSgetlpsol(a1,a2,a3,a4,a5) a1
#define GetProb_XPRSgetmipsol(a1,a2,a3) a1
#define GetProb_XPRSgetprobname(a1,a2) a1
#define GetProb_XPRSglobal(a1) a1
#define GetProb_XPRSinit(a1) NULL
#define GetProb_XPRSloadmipsol(a1,a2,a3) a1
#define GetProb_XPRSminim(a1,a2) a1
#define GetProb_XPRSpostsolve(a1) a1
#define GetProb_XPRSreadbasis(a1,a2,a3) a1
#define GetProb_XPRSreadprob(a1,a2,a3) a1
#define GetProb_XPRSsetcbmessage(a1,a2,a3) a1
#define GetProb_XPRSsetcboptnode(a1,a2,a3) a1
#define GetProb_XPRSsetdblcontrol(a1,a2,a3) a1
#define GetProb_XPRSsetintcontrol(a1,a2,a3) a1
#define GetProb_XPRSsetprobname(a1,a2) a1
#define GetProb_XPRSwritebasis(a1,a2,a3) a1
#define ERROR_EXIT(msg) \
{ \
printf("ERROR:%s(%d):%s\n", __FILE__, __LINE__, msg); \
exit(1); \
} \
#define CHECKED_RETURN(function, args) \
{ \
int _nReturn; \
if ( ((_nReturn = function args) != 0 ) ) { \
XPRSprob prob_with_failure = GetProb_##function args; \
errormsg(prob_with_failure, #function,__LINE__,_nReturn); \
} \
} \
struct FixedSearchMainContext_s {
char sProbName[256];
int nCol; /* Number of columns */
/* Global problem information */
int nGlEnt; /* Number of global entities: binary, integer, semi-continuous and partial integer variables */
int nSet; /* Number of S1 and S2 sets */
int *pGlInd; /* Column indices of the global entities */
char *pGlType; /* Global entity types */
};
struct FixedSearchLocalContext_s {
char sProbName[256];
int nCol; /* Number of columns */
/* Global problem information */
int nGlEnt; /* Number of global entities: binary, integer, semi-continuous and partial integer variables */
int nSet; /* Number of S1 and S2 sets */
int *pGlInd; /* Column indices of the global entities */
char *pGlType; /* Global entity types */
/* Bound changes */
int *pBndInd; /* Column indices of the bounds to be changed */
char *pBndType; /* New bound types - always 'B', since both the upper and lower bounds are to be changed */
double *pBndVal; /* New bound values */
/* Solution information */
double *x; /* MIP and LP solution values */
};
void *GetCurrentThreadHandle()
{
#if defined(WIN32) || defined(_WIN32)
return (void *) GetCurrentThreadId();
#else
return (void *) pthread_self();
#endif
}
void XPRS_CC Message(XPRSprob prob, void* my_object, const char *msg, int len, int msgtype)
{
struct FixedSearchMainContext_s *Context = (struct FixedSearchMainContext_s *) my_object;
switch(msgtype)
{
case 4: /* error */
case 3: /* warning */
case 2: /* dialogue */
case 1: /* information */
printf("%0p:%s\n", GetCurrentThreadHandle(), msg);
break;
default: /* exiting - buffers need flushing */
fflush(stdout);
break;
}
}
void AllocateLocalContext(struct FixedSearchMainContext_s *MainContext, struct FixedSearchLocalContext_s *LocalContext, const int bAllocateOtherwiseDeallocate)
{
if(!bAllocateOtherwiseDeallocate) {
free(LocalContext->x);
free(LocalContext->pBndInd);
free(LocalContext->pBndVal);
free(LocalContext->pBndType);
} else {
LocalContext->pGlInd = MainContext->pGlInd;
LocalContext->pGlType = MainContext->pGlType;
memcpy(LocalContext->sProbName, MainContext->sProbName, sizeof(LocalContext->sProbName));
LocalContext->nCol = MainContext->nCol;
LocalContext->nGlEnt = MainContext->nGlEnt;
LocalContext->nSet = MainContext->nSet;
/* Allocate memory for MIP solution array and check for memory shortage */
LocalContext->x=malloc(LocalContext->nCol * sizeof(double));
if (!LocalContext->x) ERROR_EXIT("malloc");
/* Allocate memory for bound arrays */
LocalContext->pBndInd=malloc(LocalContext->nGlEnt * sizeof(int));
LocalContext->pBndVal=malloc(LocalContext->nGlEnt * sizeof(double));
LocalContext->pBndType=malloc(LocalContext->nGlEnt * sizeof(char));
if (!LocalContext->pBndInd || !LocalContext->pBndVal || !LocalContext->pBndType) ERROR_EXIT("malloc");
}
}
void AllocateMainContext(XPRSprob prob, struct FixedSearchMainContext_s *Context, const int bAllocateOtherwiseDeallocate)
{
if(!bAllocateOtherwiseDeallocate) {
free(Context->pGlInd);
free(Context->pGlType);
} else {
CHECKED_RETURN( XPRSgetprobname, (prob, Context->sProbName) );
CHECKED_RETURN( XPRSgetintattrib, (prob,XPRS_COLS,&Context->nCol) );
CHECKED_RETURN( XPRSgetintattrib, (prob,XPRS_MIPENTS,&Context->nGlEnt) );
CHECKED_RETURN( XPRSgetintattrib, (prob,XPRS_SETS,&Context->nSet) );
/* Allocate memory for global entity arrays */
Context->pGlInd=malloc(Context->nCol * sizeof(int));
Context->pGlType=malloc(Context->nCol * sizeof(char));
if (!Context->pGlInd || !Context->pGlType) ERROR_EXIT("malloc");
/* Retrieve global entity information */
CHECKED_RETURN( XPRSgetglobal, (prob,&Context->nGlEnt,&Context->nSet,Context->pGlType,Context->pGlInd,NULL,NULL,NULL,NULL,NULL) );
}
}
void FixedSearch(XPRSprob parent, struct FixedSearchMainContext_s *MainContext)
{
int nBnd, i, j, iMipInfeas, iMipSols, iLoadMipSolStatus, bHasMipIncumbent;
XPRSprob probg, emptyprob;
double dRounded, dMipTol, dMipIncumbent;
char sTempProbName[256 + 32 + 1];
struct FixedSearchLocalContext_s LocalContext;
/* Only run the search for solutions with small numbers of integer infeasibilities */
CHECKED_RETURN( XPRSgetintattrib, (parent,XPRS_MIPINFEAS,&iMipInfeas) );
if(iMipInfeas > 0.25*MainContext->nGlEnt) {
goto exit_with_skip_search;
}
/* Create resources we need */
AllocateLocalContext(MainContext, &LocalContext, 1);
/* Create a problem containing the original problem */
CHECKED_RETURN( XPRScreateprob, (&probg) );
CHECKED_RETURN( XPRScopyprob, (probg, parent, LocalContext.sProbName) );
CHECKED_RETURN( XPRSpostsolve, (probg) );
/* Reset the controls of the problem and restore the name of the problem */
CHECKED_RETURN( XPRScreateprob, (&emptyprob) );
CHECKED_RETURN( XPRScopycontrols, (probg, emptyprob) );
XPRSdestroyprob(emptyprob);
/* Rename the problem so we don't get collisions with temporary files produced by the optimizer */
sprintf(sTempProbName, "%s_%0p",LocalContext.sProbName, GetCurrentThreadHandle());
CHECKED_RETURN( XPRSsetprobname, (probg,sTempProbName) );
/* Tell Optimizer to call Message whenever a message is output */
CHECKED_RETURN( XPRSsetcbmessage, (probg,Message,&LocalContext) );
/* Get information from the solution at the current node of 'parent' problem */
CHECKED_RETURN( XPRSgetintattrib, (parent,XPRS_MIPSOLS,&bHasMipIncumbent) );
CHECKED_RETURN( XPRSgetdblattrib, (parent,XPRS_MIPOBJVAL,&dMipIncumbent) );
CHECKED_RETURN( XPRSgetlpsol, (parent,LocalContext.x,NULL,NULL,NULL) );
/* Initialise bound counter */
nBnd = 0;
CHECKED_RETURN( XPRSgetdblcontrol, (parent,XPRS_MIPTOL,&dMipTol) );
/* Go through global entities */
for(i=0; i<LocalContext.nGlEnt; i++) {
/* Test whether each is a binary or integer variable */
if (LocalContext.pGlType[i] == 'B' || LocalContext.pGlType[i] == 'I') {
j = LocalContext.pGlInd[i];
/* Fix variables that are fractional */
dRounded = (double) (int)(LocalContext.x[j]+0.5);
if(fabs(dRounded - LocalContext.x[j]) <= dMipTol) {
continue;
}
LocalContext.pBndInd[nBnd] = j;
LocalContext.pBndVal[nBnd] = dRounded;
LocalContext.pBndType[nBnd] = 'B';
nBnd++;
}
}
/* Instruct Optimizer to change the bounds */
CHECKED_RETURN( XPRSchgbounds, (probg,nBnd,LocalContext.pBndInd,LocalContext.pBndType,LocalContext.pBndVal) );
printf("%0p:After global the %d binary and integer variables were fixed\n",GetCurrentThreadHandle(), nBnd);
/*
Ensure we only do a small search in the fixed problem and
use the current incumbent objective from the main problem
*/
CHECKED_RETURN( XPRSsetintcontrol, (probg,XPRS_MAXNODE,100) );
CHECKED_RETURN( XPRSsetintcontrol, (probg,XPRS_MAXMIPSOL,1) );
if(bHasMipIncumbent) {
/* Set a cut-off to help the fixed search */
CHECKED_RETURN( XPRSsetdblcontrol, (probg,XPRS_MIPABSCUTOFF,dMipIncumbent) );
}
CHECKED_RETURN( XPRSsetintcontrol, (probg,XPRS_MIPLOG,3) );
/* Read the basis for the LP relaxation to reduce run time */
CHECKED_RETURN( XPRSreadbasis, (probg,LocalContext.sProbName,"") );
/* Run the optimizer */
CHECKED_RETURN( XPRSminim, (probg,"g") );
/* If we found a solution then load it into the main problem */
CHECKED_RETURN( XPRSgetintattrib, (probg,XPRS_MIPSOLS,&iMipSols) );
if(iMipSols > 0) {
CHECKED_RETURN( XPRSgetmipsol, (probg,LocalContext.x,NULL) );
CHECKED_RETURN( XPRSloadmipsol, (parent,LocalContext.x, &iLoadMipSolStatus) );
}
/* Free the resources we have created */
XPRSdestroyprob(probg);
AllocateLocalContext(MainContext, &LocalContext, 0);
exit_with_skip_search:;
return;
}
void XPRS_CC OptNodeCb(XPRSprob my_prob, void *my_object, int *feas)
{
struct FixedSearchMainContext_s *Context = (struct FixedSearchMainContext_s *) my_object;
FixedSearch(my_prob, Context);
}
int main(void) {
XPRSprob prob;
int iMipStat;
char banner[256];
const char *sProbName = "loadmipsol";
struct FixedSearchMainContext_s Context = {0};
CHECKED_RETURN( XPRSinit, ("") );
CHECKED_RETURN( XPRSgetbanner, (banner) );
printf("%s\n", banner);
CHECKED_RETURN( XPRScreateprob, (&prob) );
CHECKED_RETURN( XPRSreadprob, (prob,sProbName,"") );
/* Register the message callback */
CHECKED_RETURN( XPRSsetcbmessage, (prob,Message,&Context) );
/* Register the fixed search routine to the optimal node callback */
CHECKED_RETURN( XPRSsetcboptnode, (prob,OptNodeCb,&Context) );
/* Make the problem difficult for the optimizer to solve */
CHECKED_RETURN( XPRSsetintcontrol, (prob,XPRS_CUTSTRATEGY,0) );
CHECKED_RETURN( XPRSsetintcontrol, (prob,XPRS_HEURSTRATEGY,0) );
CHECKED_RETURN( XPRSsetintcontrol, (prob,XPRS_SBBEST,0) );
CHECKED_RETURN( XPRSsetintcontrol, (prob,XPRS_MIPTHREADS,20) );
/* Log every node in the branch-and-bound search */
CHECKED_RETURN( XPRSsetintcontrol, (prob,XPRS_MIPLOG,3) );
/* Setup some resources we need in the callbacks */
AllocateMainContext(prob, &Context, 1);
/* Solve the LP and write out the basis (to reduce solve time of the fixed problems) */
CHECKED_RETURN( XPRSminim, (prob,"") );
CHECKED_RETURN( XPRSwritebasis, (prob,"","") );
/* Run the MIP search */
CHECKED_RETURN( XPRSglobal, (prob) );
/* Free the resources */
AllocateMainContext(prob, &Context, 0);
XPRSdestroyprob(prob);
XPRSfree();
return 0;
}
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