Detailed Description

LP diving heuristic that chooses fixings w.r.t. the fractionalities.

Author: Tobias Achterberg

#include "scip/heur_fracdiving.h"
#include "scip/heuristics.h"
#include "scip/pub_heur.h"
#include "scip/pub_message.h"
#include "scip/pub_misc.h"
#include "scip/pub_var.h"
#include "scip/scip_heur.h"
#include "scip/scip_mem.h"
#include "scip/scip_numerics.h"
#include "scip/scip_prob.h"
#include "scip/scip_sol.h"
#include <string.h>

Go to the source code of this file.

Macros
#define	HEUR_NAME "fracdiving"

#define	HEUR_DESC "LP diving heuristic that chooses fixings w.r.t. the fractionalities"

#define	HEUR_DISPCHAR SCIP_HEURDISPCHAR_DIVING

#define	HEUR_PRIORITY -1003000

#define	HEUR_FREQ 10

#define	HEUR_FREQOFS 3

#define	HEUR_MAXDEPTH -1

#define	HEUR_TIMING SCIP_HEURTIMING_AFTERLPPLUNGE

#define	HEUR_USESSUBSCIP FALSE

#define	DIVESET_DIVETYPES SCIP_DIVETYPE_INTEGRALITY \| SCIP_DIVETYPE_SOS1VARIABLE

#define	DIVESET_ISPUBLIC TRUE

#define	DEFAULT_MINRELDEPTH 0.0

#define	DEFAULT_MAXRELDEPTH 1.0

#define	DEFAULT_MAXLPITERQUOT 0.05

#define	DEFAULT_MAXLPITEROFS 1000

#define	DEFAULT_MAXDIVEUBQUOT 0.8

#define	DEFAULT_MAXDIVEAVGQUOT 0.0

#define	DEFAULT_MAXDIVEUBQUOTNOSOL 0.1

#define	DEFAULT_MAXDIVEAVGQUOTNOSOL 0.0

#define	DEFAULT_BACKTRACK TRUE

#define	DEFAULT_LPRESOLVEDOMCHGQUOT 0.15

#define	DEFAULT_LPSOLVEFREQ 0

#define	DEFAULT_ONLYLPBRANCHCANDS FALSE

#define	DEFAULT_RANDSEED 89

#define	divesetAvailableFracdiving NULL

Functions
static	SCIP_DECL_HEURCOPY (heurCopyFracdiving)

static	assert (heur !=NULL)

	assert (strcmp(SCIPheurGetName(heur), HEUR_NAME)==0)

	assert (scip !=NULL)

	assert (heurdata !=NULL)

	SCIPfreeBlockMemory (scip, &heurdata)

	SCIPheurSetData (heur, NULL)

	SCIPcreateSol (scip, &heurdata->sol, heur))

	SCIPfreeSol (scip, &heurdata->sol))

	assert (SCIPheurGetNDivesets(heur) > 0)

	assert (SCIPheurGetDivesets(heur) !=NULL)

	assert (diveset !=NULL)

	SCIPperformGenericDivingAlgorithm (scip, diveset, heurdata->sol, heur, result, nodeinfeasible, -1L, -1, -1.0, SCIP_DIVECONTEXT_SINGLE))

static	SCIP_DECL_DIVESETGETSCORE (divesetGetScoreFracdiving)

SCIP_RETCODE	SCIPincludeHeurFracdiving (SCIP *scip)

Variables
	heurdata = SCIPheurGetData(heur)

return	SCIP_OKAY

static SCIP_DIVESET *	diveset

*	result = SCIP_DIDNOTRUN

Macro Definition Documentation

◆ HEUR_NAME

#define HEUR_NAME "fracdiving"

Definition at line 46 of file heur_fracdiving.c.

◆ HEUR_DESC

#define HEUR_DESC "LP diving heuristic that chooses fixings w.r.t. the fractionalities"

Definition at line 47 of file heur_fracdiving.c.

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR SCIP_HEURDISPCHAR_DIVING

Definition at line 48 of file heur_fracdiving.c.

◆ HEUR_PRIORITY

#define HEUR_PRIORITY -1003000

Definition at line 49 of file heur_fracdiving.c.

◆ HEUR_FREQ

#define HEUR_FREQ 10

Definition at line 50 of file heur_fracdiving.c.

◆ HEUR_FREQOFS

#define HEUR_FREQOFS 3

Definition at line 51 of file heur_fracdiving.c.

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH -1

Definition at line 52 of file heur_fracdiving.c.

◆ HEUR_TIMING

#define HEUR_TIMING SCIP_HEURTIMING_AFTERLPPLUNGE

Definition at line 53 of file heur_fracdiving.c.

◆ HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP FALSE

does the heuristic use a secondary SCIP instance?

Definition at line 54 of file heur_fracdiving.c.

◆ DIVESET_DIVETYPES

#define DIVESET_DIVETYPES SCIP_DIVETYPE_INTEGRALITY | SCIP_DIVETYPE_SOS1VARIABLE

bit mask that represents all supported dive types

Definition at line 55 of file heur_fracdiving.c.

◆ DIVESET_ISPUBLIC

#define DIVESET_ISPUBLIC TRUE

is this dive set publicly available (ie., can be used by other primal heuristics?)

Definition at line 56 of file heur_fracdiving.c.

◆ DEFAULT_MINRELDEPTH

#define DEFAULT_MINRELDEPTH 0.0

minimal relative depth to start diving

Definition at line 63 of file heur_fracdiving.c.

◆ DEFAULT_MAXRELDEPTH

#define DEFAULT_MAXRELDEPTH 1.0

maximal relative depth to start diving

Definition at line 64 of file heur_fracdiving.c.

◆ DEFAULT_MAXLPITERQUOT

#define DEFAULT_MAXLPITERQUOT 0.05

maximal fraction of diving LP iterations compared to node LP iterations

Definition at line 65 of file heur_fracdiving.c.

◆ DEFAULT_MAXLPITEROFS

#define DEFAULT_MAXLPITEROFS 1000

additional number of allowed LP iterations

Definition at line 66 of file heur_fracdiving.c.

◆ DEFAULT_MAXDIVEUBQUOT

#define DEFAULT_MAXDIVEUBQUOT 0.8

maximal quotient (curlowerbound - lowerbound)/(cutoffbound - lowerbound) where diving is performed (0.0: no limit)

Definition at line 67 of file heur_fracdiving.c.

◆ DEFAULT_MAXDIVEAVGQUOT

#define DEFAULT_MAXDIVEAVGQUOT 0.0

maximal quotient (curlowerbound - lowerbound)/(avglowerbound - lowerbound) where diving is performed (0.0: no limit)

Definition at line 69 of file heur_fracdiving.c.

◆ DEFAULT_MAXDIVEUBQUOTNOSOL

#define DEFAULT_MAXDIVEUBQUOTNOSOL 0.1

maximal UBQUOT when no solution was found yet (0.0: no limit)

Definition at line 71 of file heur_fracdiving.c.

◆ DEFAULT_MAXDIVEAVGQUOTNOSOL

#define DEFAULT_MAXDIVEAVGQUOTNOSOL 0.0

maximal AVGQUOT when no solution was found yet (0.0: no limit)

Definition at line 72 of file heur_fracdiving.c.

◆ DEFAULT_BACKTRACK

#define DEFAULT_BACKTRACK TRUE

use one level of backtracking if infeasibility is encountered?

Definition at line 73 of file heur_fracdiving.c.

◆ DEFAULT_LPRESOLVEDOMCHGQUOT

#define DEFAULT_LPRESOLVEDOMCHGQUOT 0.15

percentage of immediate domain changes during probing to trigger LP resolve

Definition at line 75 of file heur_fracdiving.c.

◆ DEFAULT_LPSOLVEFREQ

#define DEFAULT_LPSOLVEFREQ 0

LP solve frequency for diving heuristics

Definition at line 76 of file heur_fracdiving.c.

◆ DEFAULT_ONLYLPBRANCHCANDS

#define DEFAULT_ONLYLPBRANCHCANDS FALSE

should only LP branching candidates be considered instead of the slower but more general constraint handler diving variable selection?

Definition at line 77 of file heur_fracdiving.c.

◆ DEFAULT_RANDSEED

#define DEFAULT_RANDSEED 89

initial random seed

Definition at line 79 of file heur_fracdiving.c.

◆ divesetAvailableFracdiving

#define divesetAvailableFracdiving NULL

Definition at line 275 of file heur_fracdiving.c.

Referenced by SCIPincludeHeurFracdiving().

Function Documentation

◆ SCIP_DECL_HEURCOPY()

static SCIP_DECL_HEURCOPY ( heurCopyFracdiving )

static

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

Definition at line 98 of file heur_fracdiving.c.

References assert(), HEUR_NAME, NULL, SCIP_CALL, SCIP_OKAY, SCIPheurGetName(), and SCIPincludeHeurFracdiving().

◆ assert() [1/7]

static assert ( heur ! = NULL )

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

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

deinitialization method of primal heuristic (called before transformed problem is freed)

References NULL.

◆ assert() [2/7]

assert ( strcmp(SCIPheurGetName(heur), HEUR_NAME) = =0 )

References HEUR_NAME.

◆ assert() [3/7]

assert ( scip ! = NULL )

References NULL.

◆ assert() [4/7]

assert ( heurdata ! = NULL )

References heurdata, and NULL.

◆ SCIPfreeBlockMemory()

SCIPfreeBlockMemory	(	scip	,
		&	heurdata )

References heurdata.

◆ SCIPheurSetData()

SCIPheurSetData	(	heur	,
		NULL	)

References NULL.

◆ SCIPcreateSol()

SCIPcreateSol	(	scip	,
		&heurdata->	sol,
		heur	)

References heurdata, and SCIP_OKAY.

◆ SCIPfreeSol()

SCIPfreeSol	(	scip	,
		&heurdata->	sol )

References heurdata, and SCIP_OKAY.

◆ assert() [5/7]

assert	(	SCIPheurGetNDivesets(heur)	,
		0	)

◆ assert() [6/7]

assert ( SCIPheurGetDivesets(heur) ! = NULL )

References diveset, and NULL.

◆ assert() [7/7]

assert ( diveset ! = NULL )

References diveset, and NULL.

◆ SCIPperformGenericDivingAlgorithm()

SCIPperformGenericDivingAlgorithm	(	scip	,
		diveset	,
		heurdata->	sol,
		heur	,
		result	,
		nodeinfeasible	,
		-	1L,
		-	1,
		-1.	0,
		SCIP_DIVECONTEXT_SINGLE	)

References diveset, heurdata, result, SCIP_DIVECONTEXT_SINGLE, and SCIP_OKAY.

◆ SCIP_DECL_DIVESETGETSCORE()

static SCIP_DECL_DIVESETGETSCORE ( divesetGetScoreFracdiving )

static

calculate score and preferred rounding direction for the candidate variable; the best candidate maximizes the score

Definition at line 197 of file heur_fracdiving.c.

References assert(), diveset, mayrounddown, mayroundup, obj, roundup, SCIP_Bool, SCIP_DIVETYPE_SOS1VARIABLE, SCIP_OKAY, SCIP_PROBINGSCORE_PENALTYRATIO, SCIP_Real, SCIPdivesetGetRandnumgen(), SCIPgetObjNorm(), SCIPisEQ(), SCIPisFeasPositive(), SCIPisPositive(), SCIPrandomGetInt(), SCIPvarGetObj(), SCIPvarIsBinary(), SCIPvarMayRoundDown(), and SCIPvarMayRoundUp().

Variable Documentation

◆ heurdata

heurdata = SCIPheurGetData(heur)

Definition at line 121 of file heur_fracdiving.c.

◆ SCIP_OKAY

return SCIP_OKAY

Definition at line 127 of file heur_fracdiving.c.

◆ diveset

diveset

Initial value:

{

SCIP_HEURDATA* heurdata

heurdata

Definition heur_actconsdiving.c:229

SCIP_HEURDATA

struct SCIP_HeurData SCIP_HEURDATA

Definition type_heur.h:77

execution method of primal heuristic

Definition at line 176 of file heur_fracdiving.c.

◆ result

* result = SCIP_DIDNOTRUN

Definition at line 186 of file heur_fracdiving.c.

Detailed Description

Macros

Functions

Variables

Macro Definition Documentation

◆ HEUR_NAME

◆ HEUR_DESC

◆ HEUR_DISPCHAR

◆ HEUR_PRIORITY

◆ HEUR_FREQ

◆ HEUR_FREQOFS

◆ HEUR_MAXDEPTH

◆ HEUR_TIMING

◆ HEUR_USESSUBSCIP

◆ DIVESET_DIVETYPES

◆ DIVESET_ISPUBLIC

◆ DEFAULT_MINRELDEPTH

◆ DEFAULT_MAXRELDEPTH

◆ DEFAULT_MAXLPITERQUOT

◆ DEFAULT_MAXLPITEROFS

◆ DEFAULT_MAXDIVEUBQUOT

◆ DEFAULT_MAXDIVEAVGQUOT

◆ DEFAULT_MAXDIVEUBQUOTNOSOL

◆ DEFAULT_MAXDIVEAVGQUOTNOSOL

◆ DEFAULT_BACKTRACK

◆ DEFAULT_LPRESOLVEDOMCHGQUOT

◆ DEFAULT_LPSOLVEFREQ

◆ DEFAULT_ONLYLPBRANCHCANDS

◆ DEFAULT_RANDSEED

◆ divesetAvailableFracdiving

Function Documentation

◆ SCIP_DECL_HEURCOPY()

◆ assert() [1/7]

◆ assert() [2/7]

◆ assert() [3/7]

◆ assert() [4/7]

◆ SCIPfreeBlockMemory()

◆ SCIPheurSetData()

◆ SCIPcreateSol()

◆ SCIPfreeSol()

◆ assert() [5/7]

◆ assert() [6/7]

◆ assert() [7/7]

◆ SCIPperformGenericDivingAlgorithm()

◆ SCIP_DECL_DIVESETGETSCORE()

Variable Documentation

◆ heurdata

◆ SCIP_OKAY

◆ diveset

◆ result