Scippy

SCIP

Solving Constraint Integer Programs

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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 <assert.h>
#include <string.h>
#include "scip/heur_simplerounding.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 'r'

#define	HEUR_PRIORITY 0

#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	SCIP_DECL_HEURFREE (heurFreeSimplerounding)

static	SCIP_DECL_HEURINIT (heurInitSimplerounding)

static	SCIP_DECL_HEUREXIT (heurExitSimplerounding)

static	SCIP_DECL_HEURINITSOL (heurInitsolSimplerounding)

static	SCIP_DECL_HEUREXITSOL (heurExitsolSimplerounding)

static	SCIP_DECL_HEUREXEC (heurExecSimplerounding)

SCIP_RETCODE	SCIPincludeHeurSimplerounding (SCIP *scip)

Macro Definition Documentation

#define HEUR_NAME "simplerounding"

Definition at line 32 of file heur_simplerounding.c.

Referenced by SCIP_DECL_HEURCOPY(), SCIP_DECL_HEUREXEC(), SCIP_DECL_HEUREXIT(), SCIP_DECL_HEURFREE(), SCIP_DECL_HEURINIT(), SCIP_DECL_HEURINITSOL(), and SCIPincludeHeurSimplerounding().

#define HEUR_DESC "simple and fast LP rounding heuristic"

Definition at line 33 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define HEUR_DISPCHAR 'r'

Definition at line 34 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define HEUR_PRIORITY 0

Definition at line 35 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define HEUR_FREQ 1

Definition at line 36 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define HEUR_FREQOFS 0

Definition at line 37 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define HEUR_MAXDEPTH -1

Definition at line 38 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define HEUR_TIMING SCIP_HEURTIMING_DURINGLPLOOP | SCIP_HEURTIMING_DURINGPRICINGLOOP

Definition at line 39 of file heur_simplerounding.c.

Referenced by SCIP_DECL_HEUREXITSOL(), and SCIPincludeHeurSimplerounding().

#define HEUR_USESSUBSCIP FALSE

does the heuristic use a secondary SCIP instance?

Definition at line 40 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

#define DEFAULT_ONCEPERNODE FALSE

should the heuristic only be called once per node?

Definition at line 42 of file heur_simplerounding.c.

Referenced by SCIPincludeHeurSimplerounding().

Function Documentation

static 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 60 of file heur_simplerounding.c.

References FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_FOUNDSOL, SCIP_OKAY, SCIP_Real, SCIP_VARSTATUS_COLUMN, SCIPadjustImplicitSolVals(), SCIPallColsInLP(), SCIPdebugMessage, SCIPfeasCeil(), SCIPfeasFloor(), SCIPisFeasIntegral(), SCIPprintSol(), SCIPsetSolVal(), SCIPtrySol(), SCIPvarGetName(), SCIPvarGetObj(), SCIPvarGetStatus(), SCIPvarMayRoundDown(), SCIPvarMayRoundUp(), and TRUE.

Referenced by performLPSimpleRounding(), and performRelaxSimpleRounding().

static 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 146 of file heur_simplerounding.c.

References NULL, performSimpleRounding(), SCIP_CALL, SCIP_HEURTIMING_DURINGPRICINGLOOP, SCIP_Longint, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIP_Real, SCIPdebugMessage, SCIPgetCutoffbound(), SCIPgetLPBranchCands(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetNLPs(), SCIPisGE(), and SCIPlinkLPSol().

Referenced by SCIP_DECL_HEUREXEC().

static 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 202 of file heur_simplerounding.c.

References NULL, performSimpleRounding(), SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPdebugMessage, SCIPfreeBufferArray, SCIPgetRelaxSolVal(), SCIPgetVarsData(), SCIPisFeasZero(), SCIPisRelaxSolValid(), and SCIPlinkRelaxSol().

Referenced by SCIP_DECL_HEUREXEC().

static SCIP_DECL_HEURCOPY ( heurCopySimplerounding )

static

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

Definition at line 277 of file heur_simplerounding.c.

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

static SCIP_DECL_HEURFREE ( heurFreeSimplerounding )

static

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

Definition at line 291 of file heur_simplerounding.c.

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

static SCIP_DECL_HEURINIT ( heurInitSimplerounding )

static

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

Definition at line 311 of file heur_simplerounding.c.

References HEUR_NAME, NULL, SCIP_CALL, SCIP_OKAY, SCIPcreateSol(), SCIPheurGetData(), and SCIPheurGetName().

static SCIP_DECL_HEUREXIT ( heurExitSimplerounding )

static

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

Definition at line 330 of file heur_simplerounding.c.

References HEUR_NAME, NULL, SCIP_CALL, SCIP_OKAY, SCIPfreeSol(), SCIPheurGetData(), and SCIPheurGetName().

static 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 347 of file heur_simplerounding.c.

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

static SCIP_DECL_HEUREXITSOL ( heurExitsolSimplerounding )

static

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

Definition at line 367 of file heur_simplerounding.c.

References HEUR_TIMING, SCIP_OKAY, and SCIPheurSetTimingmask().

static SCIP_DECL_HEUREXEC ( heurExecSimplerounding )

static

execution method of primal heuristic

Definition at line 378 of file heur_simplerounding.c.

References HEUR_NAME, NULL, performLPSimpleRounding(), performRelaxSimpleRounding(), SCIP_CALL, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_HEURTIMING_DURINGPRICINGLOOP, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIPgetCutoffbound(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetNBinVars(), SCIPgetNIntVars(), SCIPgetNLPs(), SCIPgetVars(), SCIPhasCurrentNodeLP(), SCIPheurGetData(), SCIPheurGetName(), SCIPisGE(), SCIPisRelaxSolValid(), SCIPvarMayRoundDown(), and SCIPvarMayRoundUp().

SCIP_RETCODE SCIPincludeHeurSimplerounding ( SCIP * scip )

creates the simple rounding heuristic and includes it in SCIP

Parameters

scip	SCIP data structure

Definition at line 444 of file heur_simplerounding.c.

References DEFAULT_ONCEPERNODE, HEUR_DESC, HEUR_DISPCHAR, HEUR_FREQ, HEUR_FREQOFS, HEUR_MAXDEPTH, HEUR_NAME, HEUR_PRIORITY, HEUR_TIMING, HEUR_USESSUBSCIP, NULL, SCIP_CALL, SCIP_OKAY, SCIPaddBoolParam(), SCIPallocMemory, SCIPincludeHeurBasic(), SCIPsetHeurCopy(), SCIPsetHeurExit(), SCIPsetHeurExitsol(), SCIPsetHeurFree(), SCIPsetHeurInit(), SCIPsetHeurInitsol(), and TRUE.

Referenced by SCIP_DECL_HEURCOPY(), and SCIPincludeDefaultPlugins().