Scippy

SCIP

Solving Constraint Integer Programs

heur_pscostdiving.h
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1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
6 /* Copyright (c) 2002-2024 Zuse Institute Berlin (ZIB) */
7 /* */
8 /* Licensed under the Apache License, Version 2.0 (the "License"); */
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24 
25 /**@file heur_pscostdiving.h
26  * @ingroup PRIMALHEURISTICS
27  * @brief LP diving heuristic that chooses fixings w.r.t. the pseudo cost values
28  * @author Tobias Achterberg
29  *
30  * Diving heuristic: Iteratively fixes some fractional variable and resolves the LP-relaxation, thereby simulating a
31  * depth-first-search in the tree. Pseudocost Diving chooses the variable with the smallest ratio of estimated objective
32  * increase if rounding to either direction. If the variable is significantly different from its root LP vlaue, it will
33  * be rounded into the direction it developed (see @ref heur_linesearchdiving.h), if it is close to an integral point,
34  * it will be rounded to that one, otherwise it will be rounded into the direction of lower pseudocosts. One-level
35  * backtracking is applied: If the LP gets infeasible, the last fixing is undone, and the opposite fixing is tried. If
36  * this is infeasible, too, the procedure aborts.
37  */
38 
39 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
40 
41 #ifndef __SCIP_HEUR_PSCOSTDIVING_H__
42 #define __SCIP_HEUR_PSCOSTDIVING_H__
43 
44 #include "scip/def.h"
45 #include "scip/type_retcode.h"
46 #include "scip/type_scip.h"
47 
48 #ifdef __cplusplus
49 extern "C" {
50 #endif
51 
52 /** creates the pscostdiving heuristic and includes it in SCIP
53  *
54  * @ingroup PrimalHeuristicIncludes
55  */
56 SCIP_EXPORT
58  SCIP* scip /**< SCIP data structure */
59  );
60 
61 #ifdef __cplusplus
62 }
63 #endif
64 
65 #endif
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:63
type definitions for return codes for SCIP methods
type definitions for SCIP&#39;s main datastructure
SCIP_RETCODE SCIPincludeHeurPscostdiving(SCIP *scip)
common defines and data types used in all packages of SCIP