heur_zeroobj.c File Reference

Detailed Description

heuristic that tries to solve the problem without objective. In Gurobi, this heuristic is known as "Hail Mary"

Author

Timo Berthold

Definition in file heur_zeroobj.c.

#include <assert.h>
#include <string.h>
#include "scip/heur_zeroobj.h"
#include "scip/cons_linear.h"

Go to the source code of this file.

Macros
#define	HEUR_NAME   "zeroobj"
#define	HEUR_DESC   "heuristic trying to solve the problem without objective"
#define	HEUR_DISPCHAR   'Z'
#define	HEUR_PRIORITY   100
#define	HEUR_FREQ   -1
#define	HEUR_FREQOFS   0
#define	HEUR_MAXDEPTH   0
#define	HEUR_TIMING   SCIP_HEURTIMING_BEFORENODE | SCIP_HEURTIMING_BEFOREPRESOL
#define	HEUR_USESSUBSCIP   TRUE
#define	EVENTHDLR_NAME   "Zeroobj"
#define	EVENTHDLR_DESC   "LP event handler for " HEUR_NAME " heuristic"
#define	DEFAULT_MAXNODES   1000LL /* maximum number of nodes to regard in the subproblem */
#define	DEFAULT_MINIMPROVE   0.01 /* factor by which zeroobj should at least improve the incumbent */
#define	DEFAULT_MINNODES   100LL /* minimum number of nodes to regard in the subproblem */
#define	DEFAULT_MAXLPITERS   5000LL /* maximum number of LP iterations to be performed in the subproblem */
#define	DEFAULT_NODESOFS   100LL /* number of nodes added to the contingent of the total nodes */
#define	DEFAULT_NODESQUOT   0.1 /* subproblem nodes in relation to nodes of the original problem */
#define	DEFAULT_ADDALLSOLS   FALSE /* should all subproblem solutions be added to the original SCIP? */
#define	DEFAULT_ONLYWITHOUTSOL   TRUE

Functions
static SCIP_RETCODE	createNewSol (SCIP *scip, SCIP *subscip, SCIP_VAR **subvars, SCIP_HEUR *heur, SCIP_SOL *subsol, SCIP_Bool *success)
static	SCIP_DECL_EVENTEXEC (eventExecZeroobj)
static	SCIP_DECL_HEURCOPY (heurCopyZeroobj)
static	SCIP_DECL_HEURFREE (heurFreeZeroobj)
static	SCIP_DECL_HEURINIT (heurInitZeroobj)
static	SCIP_DECL_HEUREXEC (heurExecZeroobj)
SCIP_RETCODE	SCIPapplyZeroobj (SCIP *scip, SCIP_HEUR *heur, SCIP_RESULT *result, SCIP_Real minimprove, SCIP_Longint nnodes)
SCIP_RETCODE	SCIPincludeHeurZeroobj (SCIP *scip)

Macro Definition Documentation

#define HEUR_NAME   "zeroobj"

Definition at line 29 of file heur_zeroobj.c.

Referenced by SCIP_DECL_HEURCOPY(), SCIPapplyZeroobj(), and SCIPincludeHeurZeroobj().

#define HEUR_DESC   "heuristic trying to solve the problem without objective"

Definition at line 30 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_DISPCHAR   'Z'

Definition at line 31 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_PRIORITY   100

Definition at line 32 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_FREQ   -1

Definition at line 33 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_FREQOFS   0

Definition at line 34 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_MAXDEPTH   0

Definition at line 35 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_TIMING   SCIP_HEURTIMING_BEFORENODE | SCIP_HEURTIMING_BEFOREPRESOL

Definition at line 36 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define HEUR_USESSUBSCIP   TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 37 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define EVENTHDLR_NAME   "Zeroobj"

Definition at line 40 of file heur_zeroobj.c.

Referenced by SCIP_DECL_EVENTEXEC(), and SCIPapplyZeroobj().

#define EVENTHDLR_DESC   "LP event handler for " HEUR_NAME " heuristic"

Definition at line 41 of file heur_zeroobj.c.

Referenced by SCIPapplyZeroobj().

#define DEFAULT_MAXNODES   1000LL /* maximum number of nodes to regard in the subproblem */

Definition at line 44 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_MINIMPROVE   0.01 /* factor by which zeroobj should at least improve the incumbent */

Definition at line 45 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_MINNODES   100LL /* minimum number of nodes to regard in the subproblem */

Definition at line 46 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_MAXLPITERS   5000LL /* maximum number of LP iterations to be performed in the subproblem */

Definition at line 47 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_NODESOFS   100LL /* number of nodes added to the contingent of the total nodes */

Definition at line 48 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_NODESQUOT   0.1 /* subproblem nodes in relation to nodes of the original problem */

Definition at line 49 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_ADDALLSOLS   FALSE /* should all subproblem solutions be added to the original SCIP? */

Definition at line 50 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

#define DEFAULT_ONLYWITHOUTSOL   TRUE

should heuristic only be executed if no primal solution was found, yet?

Definition at line 51 of file heur_zeroobj.c.

Referenced by SCIPincludeHeurZeroobj().

Function Documentation

static SCIP_RETCODE createNewSol ( SCIP *  scip, SCIP *  subscip, SCIP_VAR **  subvars, SCIP_HEUR *  heur, SCIP_SOL *  subsol, SCIP_Bool *  success  )

static

creates a new solution for the original problem by copying the solution of the subproblem

Parameters

scip	original SCIP data structure
subscip	SCIP structure of the subproblem
subvars	the variables of the subproblem
heur	zeroobj heuristic structure
subsol	solution of the subproblem
success	used to store whether new solution was found or not

Definition at line 78 of file heur_zeroobj.c.

References FALSE, NULL, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcreateSol(), SCIPfreeBufferArray, SCIPgetNOrigVars(), SCIPgetSolVals(), SCIPgetVarsData(), SCIPsetSolVals(), SCIPtrySolFree(), and TRUE.

Referenced by SCIPapplyZeroobj().

static SCIP_DECL_EVENTEXEC ( eventExecZeroobj  )

static

Definition at line 129 of file heur_zeroobj.c.

References EVENTHDLR_NAME, NULL, SCIP_CALL, SCIP_EVENTTYPE_NODESOLVED, SCIP_LPSOLSTAT_ITERLIMIT, SCIP_OKAY, SCIPeventGetType(), SCIPeventhdlrGetName(), SCIPgetLPSolstat(), SCIPgetNLPIterations(), and SCIPinterruptSolve().

static SCIP_DECL_HEURCOPY ( heurCopyZeroobj  )

static

copy method for primal heuristic plugins (called when SCIP copies plugins)

Definition at line 154 of file heur_zeroobj.c.

References HEUR_NAME, NULL, SCIP_CALL, SCIP_OKAY, SCIPheurGetName(), and SCIPincludeHeurZeroobj().

static SCIP_DECL_HEURFREE ( heurFreeZeroobj  )

static

destructor of primal heuristic to free user data (called when SCIP is exiting)

Definition at line 168 of file heur_zeroobj.c.

References NULL, SCIP_OKAY, SCIPfreeMemory, SCIPheurGetData(), and SCIPheurSetData().

static SCIP_DECL_HEURINIT ( heurInitZeroobj  )

static

initialization method of primal heuristic (called after problem was transformed)

Definition at line 189 of file heur_zeroobj.c.

References NULL, SCIP_OKAY, and SCIPheurGetData().

static SCIP_DECL_HEUREXEC ( heurExecZeroobj  )

static

execution method of primal heuristic

Definition at line 209 of file heur_zeroobj.c.

References MIN, NULL, SCIP_CALL, SCIP_Longint, SCIP_OKAY, SCIPapplyZeroobj(), SCIPdebugMessage, SCIPgetNNodes(), SCIPgetNObjVars(), SCIPheurGetData(), SCIPheurGetNBestSolsFound(), SCIPheurGetNCalls(), and SCIPisStopped().

SCIP_RETCODE SCIPapplyZeroobj	(	SCIP *	scip,
		SCIP_HEUR *	heur,
		SCIP_RESULT *	result,
		SCIP_Real	minimprove,
		SCIP_Longint	nnodes
	)

main procedure of the zeroobj heuristic, creates and solves a sub-SCIP

Parameters

scip	original SCIP data structure
heur	heuristic data structure
result	result data structure
minimprove	factor by which zeroobj should at least improve the incumbent
nnodes	node limit for the subproblem

Definition at line 264 of file heur_zeroobj.c.

References createNewSol(), EVENTHDLR_DESC, EVENTHDLR_NAME, FALSE, HEUR_NAME, MAX, MIN, NULL, SCIP_Bool, SCIP_CALL, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_EVENTTYPE_NODESOLVED, SCIP_FOUNDSOL, SCIP_OKAY, SCIP_PARAMSETTING_FAST, SCIP_PARAMSETTING_OFF, SCIP_PLUGINNOTFOUND, SCIP_Real, SCIPaddCoefLinear(), SCIPaddCons(), SCIPallocBufferArray, SCIPblkmem(), SCIPcalcHashtableSize(), SCIPcatchEvent(), SCIPchgVarLbGlobal(), SCIPchgVarObj(), SCIPchgVarUbGlobal(), SCIPcopy(), SCIPcreate(), SCIPcreateConsLinear(), SCIPdebugMessage, SCIPdropEvent(), SCIPerrorMessage, SCIPfeastol(), SCIPfindBranchrule(), SCIPfindConshdlr(), SCIPfindNodesel(), SCIPfree(), SCIPfreeBufferArray, SCIPgetDepth(), SCIPgetLowerbound(), SCIPgetMemExternEstim(), SCIPgetMemUsed(), SCIPgetNObjVars(), SCIPgetNSols(), SCIPgetNSolsFound(), SCIPgetRealParam(), SCIPgetSols(), SCIPgetSolvingTime(), SCIPgetUpperbound(), SCIPgetVarsData(), SCIPhashmapCreate(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPheurGetData(), SCIPheurGetNCalls(), SCIPincludeEventhdlrBasic(), SCIPinfinity(), SCIPisFeasZero(), SCIPisInfinity(), SCIPisParamFixed(), SCIPprintStatistics(), SCIPreleaseCons(), SCIPsetBoolParam(), SCIPsetIntParam(), SCIPsetLongintParam(), SCIPsetPresolving(), SCIPsetRealParam(), SCIPsetSeparating(), SCIPsetSubscipsOff(), SCIPsolve(), SCIPsumepsilon(), SCIPtransformProb(), SCIPvarGetLbGlobal(), SCIPvarGetObj(), SCIPvarGetUbGlobal(), SCIPwarningMessage(), and TRUE.

Referenced by SCIP_DECL_HEUREXEC().

SCIP_RETCODE SCIPincludeHeurZeroobj

(

SCIP *

scip

)

creates the zeroobj primal heuristic and includes it in SCIP

Parameters

scip	SCIP data structure

Definition at line 566 of file heur_zeroobj.c.

References DEFAULT_ADDALLSOLS, DEFAULT_MAXLPITERS, DEFAULT_MAXNODES, DEFAULT_MINIMPROVE, DEFAULT_MINNODES, DEFAULT_NODESOFS, DEFAULT_NODESQUOT, DEFAULT_ONLYWITHOUTSOL, FALSE, HEUR_DESC, HEUR_DISPCHAR, HEUR_FREQ, HEUR_FREQOFS, HEUR_MAXDEPTH, HEUR_NAME, HEUR_PRIORITY, HEUR_TIMING, HEUR_USESSUBSCIP, NULL, SCIP_CALL, SCIP_LONGINT_MAX, SCIP_OKAY, SCIPaddBoolParam(), SCIPaddLongintParam(), SCIPaddRealParam(), SCIPallocMemory, SCIPincludeHeurBasic(), SCIPsetHeurCopy(), SCIPsetHeurFree(), SCIPsetHeurInit(), and TRUE.

Referenced by SCIP_DECL_HEURCOPY(), and SCIPincludeDefaultPlugins().