presol_dualcomp.c File Reference

Detailed Description

dual compensation presolver

Author

Dieter Weninger

This presolver looks for variables with i) objcoef >= 0 and exactly one downlock ii) objcoef <= 0 and exactly one uplock and fixes the variable in case i) at the lower bound and in case ii) at the upper bound if a combination of singleton continuous variables can compensate the downlock in case i) and the uplock in case ii).

Definition in file presol_dualcomp.c.

#include "blockmemshell/memory.h"
#include "scip/presol_dualcomp.h"
#include "scip/pub_matrix.h"
#include "scip/pub_message.h"
#include "scip/pub_presol.h"
#include "scip/pub_var.h"
#include "scip/scip_general.h"
#include "scip/scip_mem.h"
#include "scip/scip_message.h"
#include "scip/scip_nlp.h"
#include "scip/scip_numerics.h"
#include "scip/scip_param.h"
#include "scip/scip_presol.h"
#include "scip/scip_pricer.h"
#include "scip/scip_prob.h"
#include "scip/scip_probing.h"
#include "scip/scip_var.h"
#include <string.h>

Go to the source code of this file.

Macros
#define	PRESOL_NAME   "dualcomp"
#define	PRESOL_DESC   "compensate single up-/downlocks by singleton continuous variables"
#define	PRESOL_PRIORITY   -50
#define	PRESOL_MAXROUNDS   -1
#define	PRESOL_TIMING   SCIP_PRESOLTIMING_EXHAUSTIVE /* timing of the presolver (fast, medium, or exhaustive) */
#define	DEFAULT_COMP_ONLY_DIS_VARS   FALSE

Typedefs
typedef enum Fixingdirection	FIXINGDIRECTION
typedef enum Lockcompensation	LOCKCOMPENSATION

Enumerations
enum	Fixingdirection {   FIXATLB = -1 ,   NOFIX = 0 ,   FIXATUB = 1 ,   FIXATLB = -1 ,   NOFIX = 0 ,   FIXATUB = 1 ,   FIXATLB = -1 ,   NOFIX = 0 ,   FIXATUB = 1 ,   FIXATLB = -1 ,   NOFIX = 0 ,   FIXATUB = 1 }
enum	Lockcompensation {   COMPENSATE_DOWNLOCK = 0 ,   COMPENSATE_UPLOCK = 1 }

Functions
static SCIP_RETCODE	compensateVarLock (SCIP *scip, SCIP_MATRIX *matrix, int col, int row, SCIP_Real val, SCIP_Bool twosides, LOCKCOMPENSATION compensation, FIXINGDIRECTION *varstofix, int *nfixings)
static	SCIP_DECL_PRESOLCOPY (presolCopyDualcomp)
static	SCIP_DECL_PRESOLEXEC (presolExecDualcomp)
static	SCIP_DECL_PRESOLFREE (presolFreeDualcomp)
SCIP_RETCODE	SCIPincludePresolDualcomp (SCIP *scip)

Macro Definition Documentation

PRESOL_NAME

#define PRESOL_NAME   "dualcomp"

Definition at line 59 of file presol_dualcomp.c.

PRESOL_DESC

#define PRESOL_DESC   "compensate single up-/downlocks by singleton continuous variables"

Definition at line 60 of file presol_dualcomp.c.

PRESOL_PRIORITY

#define PRESOL_PRIORITY   -50

priority of the presolver (>= 0: before, < 0: after constraint handlers)

Definition at line 66 of file presol_dualcomp.c.

PRESOL_MAXROUNDS

#define PRESOL_MAXROUNDS   -1

maximal number of presolving rounds the presolver participates in (-1: no limit)

Definition at line 67 of file presol_dualcomp.c.

PRESOL_TIMING

#define PRESOL_TIMING   SCIP_PRESOLTIMING_EXHAUSTIVE /* timing of the presolver (fast, medium, or exhaustive) */

Definition at line 68 of file presol_dualcomp.c.

DEFAULT_COMP_ONLY_DIS_VARS

#define DEFAULT_COMP_ONLY_DIS_VARS   FALSE

should only discrete variables be compensated?

Definition at line 70 of file presol_dualcomp.c.

Typedef Documentation

FIXINGDIRECTION

typedef enum Fixingdirection FIXINGDIRECTION

Definition at line 89 of file presol_dualcomp.c.

LOCKCOMPENSATION

typedef enum Lockcompensation LOCKCOMPENSATION

Definition at line 97 of file presol_dualcomp.c.

Enumeration Type Documentation

Fixingdirection

enum Fixingdirection

type of fixing direction

Enumerator
FIXATLB	fix variable at lower bound
NOFIX	do not fix variable
FIXATUB	fix variable at upper bound
FIXATLB	fix variable at lower bound
NOFIX	do not fix variable
FIXATUB	fix variable at upper bound
FIXATLB
NOFIX	fix variable at its lower bound
FIXATUB	no fixing
FIXATLB	fix variable at lower bound
NOFIX	do not fix variable
FIXATUB	fix variable at upper bound

Definition at line 83 of file presol_dualcomp.c.

Lockcompensation

enum Lockcompensation

type of variable lock compensation

Enumerator
COMPENSATE_DOWNLOCK
COMPENSATE_UPLOCK

Definition at line 92 of file presol_dualcomp.c.

Function Documentation

compensateVarLock()

static SCIP_RETCODE compensateVarLock ( SCIP *  scip, SCIP_MATRIX *  matrix, int  col, int  row, SCIP_Real  val, SCIP_Bool  twosides, LOCKCOMPENSATION  compensation, FIXINGDIRECTION *  varstofix, int *  nfixings  )

static

try to compensate a variable with a single opposite lock by using singleton continuous variables

Parameters

scip	SCIP main data structure
matrix	matrix containing the constraints
col	variable fixing candidate
row	row index with opposite lock
val	value of fixing candidate in the opposite lock constraint
twosides	flag indicating that two sides are present
compensation	type of lock compensation
varstofix	array holding fixing information
nfixings	number of possible fixings

Definition at line 106 of file presol_dualcomp.c.

References COMPENSATE_DOWNLOCK, COMPENSATE_UPLOCK, FALSE, FIXATLB, FIXATUB, NOFIX, NULL, SCIP_Bool, SCIP_LOCKTYPE_MODEL, SCIP_OKAY, SCIP_Real, SCIP_VARTYPE_CONTINUOUS, SCIPdebugMsg, SCIPisGT(), SCIPisInfinity(), SCIPisLE(), SCIPisLT(), SCIPmatrixGetColNDownlocks(), SCIPmatrixGetColNNonzs(), SCIPmatrixGetColNUplocks(), SCIPmatrixGetNColumns(), SCIPmatrixGetNRows(), SCIPmatrixGetRowIdxPtr(), SCIPmatrixGetRowLhs(), SCIPmatrixGetRowNNonzs(), SCIPmatrixGetRowRhs(), SCIPmatrixGetRowValPtr(), SCIPmatrixGetVar(), SCIPmatrixPrintRow(), SCIPvarGetLbGlobal(), SCIPvarGetName(), SCIPvarGetNLocksDownType(), SCIPvarGetNLocksUpType(), SCIPvarGetObj(), SCIPvarGetType(), SCIPvarGetUbGlobal(), SCIPvarIsIntegral(), and TRUE.

Referenced by SCIP_DECL_PRESOLEXEC().

SCIP_DECL_PRESOLCOPY()

static SCIP_DECL_PRESOLCOPY ( presolCopyDualcomp  )

static

copy method for constraint handler plugins (called when SCIP copies plugins)

Definition at line 511 of file presol_dualcomp.c.

References NULL, PRESOL_NAME, SCIP_CALL, SCIP_OKAY, SCIPincludePresolDualcomp(), and SCIPpresolGetName().

SCIP_DECL_PRESOLEXEC()

static SCIP_DECL_PRESOLEXEC ( presolExecDualcomp  )

static

execution method of presolver

Definition at line 525 of file presol_dualcomp.c.

References BMSclearMemoryArray, COMPENSATE_DOWNLOCK, COMPENSATE_UPLOCK, compensateVarLock(), FALSE, FIXATLB, FIXATUB, NULL, SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_LOCKTYPE_MODEL, SCIP_OKAY, SCIP_Real, SCIP_STAGE_PRESOLVING, SCIP_SUCCESS, SCIPallocBufferArray, SCIPallowStrongDualReds(), SCIPdebugMsg, SCIPfixVar(), SCIPfreeBufferArray, SCIPgetNActivePricers(), SCIPgetNContVars(), SCIPgetStage(), SCIPinProbing(), SCIPisEQ(), SCIPisGE(), SCIPisGT(), SCIPisInfinity(), SCIPisLE(), SCIPisLT(), SCIPisNLPEnabled(), SCIPisStopped(), SCIPisZero(), SCIPmatrixCreate(), SCIPmatrixFree(), SCIPmatrixGetColIdxPtr(), SCIPmatrixGetColNDownlocks(), SCIPmatrixGetColNNonzs(), SCIPmatrixGetColNUplocks(), SCIPmatrixGetColValPtr(), SCIPmatrixGetNColumns(), SCIPmatrixGetRowLhs(), SCIPmatrixGetRowRhs(), SCIPmatrixGetVar(), SCIPmatrixIsRowRhsInfinity(), SCIPpresolGetData(), SCIPvarGetLbGlobal(), SCIPvarGetName(), SCIPvarGetNLocksDownType(), SCIPvarGetNLocksUpType(), SCIPvarGetObj(), SCIPvarGetUbGlobal(), SCIPvarIsIntegral(), and TRUE.

SCIP_DECL_PRESOLFREE()

static SCIP_DECL_PRESOLFREE ( presolFreeDualcomp  )

static

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

Definition at line 827 of file presol_dualcomp.c.

References NULL, SCIP_OKAY, SCIPfreeBlockMemory, SCIPpresolGetData(), and SCIPpresolSetData().