type_heur.h File Reference

Detailed Description

type definitions for primal heuristics

Author

Tobias Achterberg

Timo Berthold

This file defines the interface for primal heuristics implemented in C.

• Instructions for implementing a primal heuristic
• List of available primal heuristics
• C++ wrapper class

Definition in file type_heur.h.

#include "scip/def.h"
#include "scip/type_scip.h"
#include "scip/type_result.h"
#include "scip/type_timing.h"

Go to the source code of this file.

Macros
#define	SCIP_DIVETYPE_NONE   0x000u
#define	SCIP_DIVETYPE_INTEGRALITY   0x001u
#define	SCIP_DIVETYPE_SOS1VARIABLE   0x002u
#define	SCIP_DECL_HEURCOPY(x)   SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
#define	SCIP_DECL_HEURFREE(x)   SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
#define	SCIP_DECL_HEURINIT(x)   SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
#define	SCIP_DECL_HEUREXIT(x)   SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
#define	SCIP_DECL_HEURINITSOL(x)   SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
#define	SCIP_DECL_HEUREXITSOL(x)   SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
#define	SCIP_DECL_HEUREXEC(x)
#define	SCIP_DECL_DIVESETGETSCORE(x)

Typedefs
typedef unsigned int	SCIP_DIVETYPE
typedef struct SCIP_Heur	SCIP_HEUR
typedef struct SCIP_HeurData	SCIP_HEURDATA
typedef struct SCIP_Diveset	SCIP_DIVESET

Macro Definition Documentation

#define SCIP_DIVETYPE_NONE   0x000u

represents different methods for a dive set to explore the next children no method specified

Definition at line 44 of file type_heur.h.

#define SCIP_DIVETYPE_INTEGRALITY   0x001u

use branching on a variable by shrinking the domain in the child nodes

Definition at line 45 of file type_heur.h.

#define SCIP_DIVETYPE_SOS1VARIABLE   0x002u

branch on a variable solution value by exploiting special-ordered set conflict structure

Definition at line 46 of file type_heur.h.

#define SCIP_DECL_HEURCOPY

(

x

)

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)

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

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself

Definition at line 60 of file type_heur.h.

#define SCIP_DECL_HEURFREE

(

x

)

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)

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

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself

Definition at line 68 of file type_heur.h.

#define SCIP_DECL_HEURINIT

(

x

)

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)

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

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself

Definition at line 76 of file type_heur.h.

#define SCIP_DECL_HEUREXIT

(

x

)

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)

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

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself

Definition at line 84 of file type_heur.h.

#define SCIP_DECL_HEURINITSOL

(

x

)

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)

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

This method is called when the presolving was finished and the branch and bound process is about to begin. The primal heuristic may use this call to initialize its branch and bound specific data.

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself

Definition at line 95 of file type_heur.h.

#define SCIP_DECL_HEUREXITSOL

(

x

)

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)

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

This method is called before the branch and bound process is freed. The primal heuristic should use this call to clean up its branch and bound data.

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself

Definition at line 106 of file type_heur.h.

#define SCIP_DECL_HEUREXEC

(

x

)

Value:

SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur, SCIP_HEURTIMING heurtiming, \
      SCIP_Bool nodeinfeasible, SCIP_RESULT* result)

execution method of primal heuristic

Searches for feasible primal solutions. The method is called in the node processing loop.

input:

• scip : SCIP main data structure
• heur : the primal heuristic itself
• heurtiming : current point in the node solving loop
• nodeinfeasible : was the current node already detected to be infeasible?
• result : pointer to store the result of the heuristic call

possible return values for *result:

• SCIP_FOUNDSOL : at least one feasible primal solution was found
• SCIP_DIDNOTFIND : the heuristic searched, but did not find a feasible solution
• SCIP_DIDNOTRUN : the heuristic was skipped
• SCIP_DELAYED : the heuristic was skipped, but should be called again as soon as possible, disregarding its frequency

Definition at line 126 of file type_heur.h.

#define SCIP_DECL_DIVESETGETSCORE

(

x

)

Value:

SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, SCIP_DIVETYPE divetype, SCIP_VAR* cand, SCIP_Real candsol, SCIP_Real candsfrac, \
   SCIP_Real* score, SCIP_Bool* roundup)

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

input:

• scip : SCIP main data structure
• cand : Candidate variable for which the score should be determined
• divetype : represents different methods for a dive set to explore the next children
• candsol : solution value of variable in LP relaxation solution
• candsfrac : fractional part of solution value of variable
• score : pointer for diving score value - small scores are preferred
• roundup : pointer to store whether the preferred rounding direction is upwards

returns SCIP_OKAY if everything worked, otherwise, a suitable error code

Definition at line 146 of file type_heur.h.

Typedef Documentation

typedef unsigned int SCIP_DIVETYPE

Definition at line 48 of file type_heur.h.

typedef struct SCIP_Heur SCIP_HEUR

primal heuristic

Definition at line 50 of file type_heur.h.

typedef struct SCIP_HeurData SCIP_HEURDATA

locally defined primal heuristic data

Definition at line 51 of file type_heur.h.

typedef struct SCIP_Diveset SCIP_DIVESET

common parameters for all diving heuristics

Definition at line 52 of file type_heur.h.