Detailed Description

simple and fast LP rounding heuristic

Author: Tobias Achterberg; Marc Pfetsch

The heuristic also tries to round relaxation solutions if available.

Definition in file heur_simplerounding.c.

#include "blockmemshell/memory.h"
#include "scip/heur_simplerounding.h"
#include "scip/pub_heur.h"
#include "scip/pub_message.h"
#include "scip/pub_var.h"
#include "scip/scip_branch.h"
#include "scip/scip_heur.h"
#include "scip/scip_lp.h"
#include "scip/scip_mem.h"
#include "scip/scip_message.h"
#include "scip/scip_numerics.h"
#include "scip/scip_param.h"
#include "scip/scip_prob.h"
#include "scip/scip_sol.h"
#include "scip/scip_solvingstats.h"
#include "scip/scip_var.h"
#include <string.h>

Go to the source code of this file.

Macros
#define	HEUR_NAME "simplerounding"
#define	HEUR_DESC "simple and fast LP rounding heuristic"
#define	HEUR_DISPCHAR SCIP_HEURDISPCHAR_ROUNDING
#define	HEUR_PRIORITY -30
#define	HEUR_FREQ 1
#define	HEUR_FREQOFS 0
#define	HEUR_MAXDEPTH -1
#define	HEUR_TIMING SCIP_HEURTIMING_DURINGLPLOOP \| SCIP_HEURTIMING_DURINGPRICINGLOOP
#define	HEUR_USESSUBSCIP FALSE
#define	DEFAULT_ONCEPERNODE FALSE

Functions
static SCIP_RETCODE	performSimpleRounding (SCIP scip, SCIP_SOL sol, SCIP_VAR *cands, SCIP_Real candssol, int ncands, SCIP_RESULT *result)
static SCIP_RETCODE	performLPSimpleRounding (SCIP scip, SCIP_HEURDATA heurdata, SCIP_HEURTIMING heurtiming, SCIP_RESULT *result)
static SCIP_RETCODE	performRelaxSimpleRounding (SCIP scip, SCIP_HEURDATA heurdata, SCIP_RESULT *result)
static	SCIP_DECL_HEURCOPY (heurCopySimplerounding)
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))
static	SCIP_DECL_HEURINITSOL (heurInitsolSimplerounding)
static	SCIP_DECL_HEUREXITSOL (heurExitsolSimplerounding)
	assert (SCIPhasCurrentNodeLP(scip))
	assert (result !=NULL)
	if (nbinintvars==0)
	performLPSimpleRounding (scip, heurdata, heurtiming, result))
	performRelaxSimpleRounding (scip, heurdata, result))
SCIP_RETCODE	SCIPincludeHeurSimplerounding (SCIP *scip)

Variables
	heurdata = SCIPheurGetData(heur)
return	SCIP_OKAY
heurdata	lastlp = -1
heurdata	nroundablevars = -1
static int	nbinintvars
*	result = SCIP_DIDNOTRUN

Macro Definition Documentation

◆ HEUR_NAME

#define HEUR_NAME "simplerounding"

Definition at line 54 of file heur_simplerounding.c.

◆ HEUR_DESC

#define HEUR_DESC "simple and fast LP rounding heuristic"

Definition at line 55 of file heur_simplerounding.c.

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR SCIP_HEURDISPCHAR_ROUNDING

Definition at line 56 of file heur_simplerounding.c.

◆ HEUR_PRIORITY

#define HEUR_PRIORITY -30

Definition at line 57 of file heur_simplerounding.c.

◆ HEUR_FREQ

#define HEUR_FREQ 1

Definition at line 58 of file heur_simplerounding.c.

◆ HEUR_FREQOFS

#define HEUR_FREQOFS 0

Definition at line 59 of file heur_simplerounding.c.

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH -1

Definition at line 60 of file heur_simplerounding.c.

◆ HEUR_TIMING

#define HEUR_TIMING SCIP_HEURTIMING_DURINGLPLOOP | SCIP_HEURTIMING_DURINGPRICINGLOOP

Definition at line 61 of file heur_simplerounding.c.

◆ HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP FALSE

does the heuristic use a secondary SCIP instance?

Definition at line 62 of file heur_simplerounding.c.

◆ DEFAULT_ONCEPERNODE

#define DEFAULT_ONCEPERNODE FALSE

should the heuristic only be called once per node?

Definition at line 64 of file heur_simplerounding.c.

Function Documentation

◆ performSimpleRounding()

SCIP_RETCODE performSimpleRounding	(	SCIP *	scip,
		SCIP_SOL *	sol,
		SCIP_VAR **	cands,
		SCIP_Real *	candssol,
		int	ncands,
		SCIP_RESULT *	result )

static

perform rounding

Parameters

scip	SCIP main data structure
sol	solution to round
cands	candidate variables
candssol	solutions of candidate variables
ncands	number of candidates
result	pointer to store the result of the heuristic call

Definition at line 82 of file heur_simplerounding.c.

References assert(), c, FALSE, mayrounddown, mayroundup, NULL, result, SCIP_Bool, SCIP_CALL, SCIP_FOUNDSOL, SCIP_OKAY, SCIP_Real, SCIP_VARSTATUS_COLUMN, SCIPadjustImplicitSolVals(), SCIPallColsInLP(), SCIPdebugMsg, SCIPfeasCeil(), SCIPfeasFloor(), SCIPisFeasIntegral(), SCIPprintSol(), SCIPsetSolVal(), SCIPtrySol(), SCIPvarGetName(), SCIPvarGetObj(), SCIPvarGetStatus(), SCIPvarIsImpliedIntegral(), SCIPvarMayRoundDown(), SCIPvarMayRoundUp(), sol, TRUE, and var.

Referenced by performLPSimpleRounding(), and performRelaxSimpleRounding().

◆ performLPSimpleRounding() [1/2]

SCIP_RETCODE performLPSimpleRounding	(	SCIP *	scip,
		SCIP_HEURDATA *	heurdata,
		SCIP_HEURTIMING	heurtiming,
		SCIP_RESULT *	result )

static

perform LP-rounding

Parameters

scip	SCIP main data structure
heurdata	heuristic data
heurtiming	heuristic timing mask
result	pointer to store the result of the heuristic call

Definition at line 185 of file heur_simplerounding.c.

References assert(), heurdata, lpcands, lpcandssol, nlpcands, nlps, NULL, performSimpleRounding(), result, SCIP_CALL, SCIP_HEURTIMING_DURINGPRICINGLOOP, SCIP_Longint, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIP_Real, SCIPdebugMsg, SCIPgetCutoffbound(), SCIPgetLPBranchCands(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetNLPs(), SCIPisGE(), SCIPlinkLPSol(), and sol.

◆ performRelaxSimpleRounding() [1/2]

SCIP_RETCODE performRelaxSimpleRounding	(	SCIP *	scip,
		SCIP_HEURDATA *	heurdata,
		SCIP_RESULT *	result )

static

perform relaxation solution rounding

Parameters

scip	SCIP main data structure
heurdata	heuristic data
result	pointer to store the result of the heuristic call

Definition at line 245 of file heur_simplerounding.c.

References assert(), heurdata, NULL, performSimpleRounding(), result, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPdebugMsg, SCIPfreeBufferArray, SCIPgetRelaxSolVal(), SCIPgetVarsData(), SCIPisFeasIntegral(), SCIPisRelaxSolValid(), SCIPlinkRelaxSol(), sol, and vars.

◆ SCIP_DECL_HEURCOPY()

SCIP_DECL_HEURCOPY ( heurCopySimplerounding )

static

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

Definition at line 338 of file heur_simplerounding.c.

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

◆ assert() [1/6]

assert ( heur ! = NULL )

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

References NULL.

◆ assert() [2/6]

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

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

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

References HEUR_NAME.

◆ assert() [3/6]

assert ( scip ! = NULL )

References NULL.

◆ assert() [4/6]

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.

◆ SCIPfreeSol()

SCIPfreeSol	(	scip	,
		&heurdata->	sol )

References heurdata, and SCIP_OKAY.

◆ SCIP_DECL_HEURINITSOL()

SCIP_DECL_HEURINITSOL ( heurInitsolSimplerounding )

static

solving process initialization method of primal heuristic (called when branch and bound process is about to begin)

Definition at line 408 of file heur_simplerounding.c.

References assert(), HEUR_NAME, heurdata, NULL, SCIP_HEURTIMING_AFTERLPNODE, SCIP_OKAY, SCIPheurGetData(), SCIPheurGetName(), and SCIPheurSetTimingmask().

◆ SCIP_DECL_HEUREXITSOL()

SCIP_DECL_HEUREXITSOL ( heurExitsolSimplerounding )

static

solving process deinitialization method of primal heuristic (called before branch and bound process data is freed)

Definition at line 428 of file heur_simplerounding.c.

References HEUR_TIMING, SCIP_OKAY, and SCIPheurSetTimingmask().

◆ assert() [5/6]

assert ( SCIPhasCurrentNodeLP(scip) )

References HEUR_NAME.

◆ assert() [6/6]

assert ( result ! = NULL )

References NULL, and result.

◆ if()

if ( nbinintvars = = 0 )

Definition at line 454 of file heur_simplerounding.c.

References heurdata, i, nbinintvars, NULL, SCIP_HEURTIMING_DURINGPRICINGLOOP, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIPisRelaxSolValid(), and vars.

◆ performLPSimpleRounding() [2/2]

performLPSimpleRounding	(	scip	,
		heurdata	,
		heurtiming	,
		result	)

References heurdata, and result.

◆ performRelaxSimpleRounding() [2/2]

performRelaxSimpleRounding	(	scip	,
		heurdata	,
		result	)

References heurdata, result, and SCIP_OKAY.

Variable Documentation

◆ heurdata

heurdata = SCIPheurGetData(heur)

Definition at line 361 of file heur_simplerounding.c.

◆ SCIP_OKAY

return SCIP_OKAY

Definition at line 366 of file heur_simplerounding.c.

◆ lastlp

heurdata lastlp = -1

Definition at line 382 of file heur_simplerounding.c.

◆ nroundablevars

heurdata nroundablevars = -1

Definition at line 383 of file heur_simplerounding.c.

◆ nbinintvars

nbinintvars

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 442 of file heur_simplerounding.c.

Referenced by alnsFixMoreVariables(), alnsUnfixVariables(), DECL_VARFIXINGS(), DECL_VARFIXINGS(), fillKernels(), fixMatchingSolutionValues(), fixMatchingSolutionValues(), if(), LNSFixMoreVariables(), LNSUnfixVariables(), neighborhoodFixVariables(), neighborhoodFixVariables(), SCIP_DECL_HEUREXEC(), and SCIPvariablegraphBreadthFirst().

◆ result

* result = SCIP_DIDNOTRUN

Definition at line 448 of file heur_simplerounding.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

◆ DEFAULT_ONCEPERNODE

Function Documentation

◆ performSimpleRounding()

◆ performLPSimpleRounding() [1/2]

◆ performRelaxSimpleRounding() [1/2]

◆ SCIP_DECL_HEURCOPY()

◆ assert() [1/6]

◆ assert() [2/6]

◆ assert() [3/6]

◆ assert() [4/6]

◆ SCIPfreeBlockMemory()

◆ SCIPheurSetData()

◆ SCIPcreateSol()

◆ SCIPfreeSol()

◆ SCIP_DECL_HEURINITSOL()

◆ SCIP_DECL_HEUREXITSOL()

◆ assert() [5/6]

◆ assert() [6/6]

◆ if()

◆ performLPSimpleRounding() [2/2]

◆ performRelaxSimpleRounding() [2/2]

Variable Documentation

◆ heurdata

◆ SCIP_OKAY

◆ lastlp

◆ nroundablevars

◆ nbinintvars

◆ result