1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 2 /* */ 3 /* This file is part of the program and library */ 4 /* SCIP --- Solving Constraint Integer Programs */ 5 /* */ 6 /* Copyright (c) 2002-2023 Zuse Institute Berlin (ZIB) */ 7 /* */ 8 /* Licensed under the Apache License, Version 2.0 (the "License"); */ 9 /* you may not use this file except in compliance with the License. */ 10 /* You may obtain a copy of the License at */ 11 /* */ 12 /* http://www.apache.org/licenses/LICENSE-2.0 */ 13 /* */ 14 /* Unless required by applicable law or agreed to in writing, software */ 15 /* distributed under the License is distributed on an "AS IS" BASIS, */ 16 /* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */ 17 /* See the License for the specific language governing permissions and */ 18 /* limitations under the License. */ 19 /* */ 20 /* You should have received a copy of the Apache-2.0 license */ 21 /* along with SCIP; see the file LICENSE. If not visit scipopt.org. */ 22 /* */ 23 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 24 25 /**@file heur_subnlp.h 26 * @ingroup PRIMALHEURISTICS 27 * @brief NLP local search primal heuristic using sub-SCIPs 28 * @author Stefan Vigerske 29 * 30 * This heuristic applies a NLP local search to a nonlinear CIP after fixing all discrete variables. 31 * That is, the CIP is copied, all discrete variables are fixed, presolving is applied, 32 * and if the resulting CIP has a nonlinear relaxation, then it is tried to solve this relaxation 33 * by an NLP solver. 34 * The heuristic only runs if continuous nonlinearities are present (@ref SCIPhasNLPContinuousNonlinearity()). 35 * 36 * Fixing values for discrete values are either taken from a solution of the LP relaxation which 37 * satisfies all integrality constraints, or are provided by SCIPupdateStartpointHeurSubNlp(). 38 * 39 * This heuristic is orthogonal to the undercover heuristic (@ref heur_undercover.h), which fixes 40 * variables in a nonlinear CIP in a way that a (possibly mixed-integer) linear subproblem is obtained. 41 */ 42 43 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 44 45 #ifndef HEUR_SUBNLP_H_ 46 #define HEUR_SUBNLP_H_ 47 48 #include "scip/def.h" 49 #include "scip/type_heur.h" 50 #include "scip/type_result.h" 51 #include "scip/type_retcode.h" 52 #include "scip/type_scip.h" 53 #include "scip/type_sol.h" 54 #include "scip/type_var.h" 55 56 #ifdef __cplusplus 57 extern "C" { 58 #endif 59 60 /** creates the NLP local search primal heuristic and includes it in SCIP 61 * 62 * @ingroup PrimalHeuristicIncludes 63 */ 64 SCIP_EXPORT 65 SCIP_RETCODE SCIPincludeHeurSubNlp( 66 SCIP* scip /**< SCIP data structure */ 67 ); 68 69 /**@addtogroup PRIMALHEURISTICS 70 * 71 * @{ 72 */ 73 74 /** main procedure of the subNLP heuristic */ 75 SCIP_EXPORT 76 SCIP_RETCODE SCIPapplyHeurSubNlp( 77 SCIP* scip, /**< original SCIP data structure */ 78 SCIP_HEUR* heur, /**< heuristic data structure */ 79 SCIP_RESULT* result, /**< pointer to store result of: solution found, no solution found, or fixing is infeasible (cutoff) */ 80 SCIP_SOL* refpoint, /**< point to take fixation of discrete variables from, and startpoint for NLP solver; if NULL, then LP solution is used */ 81 SCIP_SOL* resultsol /**< a solution where to store found solution values, if any, or NULL if to try adding to SCIP */ 82 ); 83 84 /** updates the starting point for the NLP heuristic 85 * 86 * Is called, for example, by a constraint handler that handles nonlinear constraints when a check on feasibility of a solution fails. 87 */ 88 SCIP_EXPORT 89 SCIP_RETCODE SCIPupdateStartpointHeurSubNlp( 90 SCIP* scip, /**< SCIP data structure */ 91 SCIP_HEUR* heur, /**< subNLP heuristic */ 92 SCIP_SOL* solcand, /**< solution candidate */ 93 SCIP_Real violation /**< constraint violation of solution candidate */ 94 ); 95 96 /** gets startpoint candidate to be used in next call to NLP heuristic, or NULL if none */ 97 SCIP_EXPORT 98 SCIP_SOL* SCIPgetStartCandidateHeurSubNlp( 99 SCIP* scip, /**< original SCIP data structure */ 100 SCIP_HEUR* heur /**< heuristic data structure */ 101 ); 102 103 /** @} */ 104 105 #ifdef __cplusplus 106 } 107 #endif 108 109 #endif /*HEUR_SUBNLP_H_*/ 110