# source:stable/1.14/Clp/src/ClpPredictorCorrector.hpp@2468

Last change on this file since 2468 was 1665, checked in by lou, 9 years ago

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1/* \$Id: ClpPredictorCorrector.hpp 1665 2011-01-04 17:55:54Z stefan \$ */
5/*
6   Authors
7
8   John Forrest
9
10 */
11#ifndef ClpPredictorCorrector_H
12#define ClpPredictorCorrector_H
13
14#include "ClpInterior.hpp"
15
16/** This solves LPs using the predictor-corrector method due to Mehrotra.
17    It also uses multiple centrality corrections as in Gondzio.
18
19    See;
20    S. Mehrotra, "On the implementation of a primal-dual interior point method",
21    SIAM Journal on optimization, 2 (1992)
22    J. Gondzio, "Multiple centraility corrections in a primal-dual method for linear programming",
23    Computational Optimization and Applications",6 (1996)
24
25
26    It is rather basic as Interior point is not my speciality
27
28    It inherits from ClpInterior.  It has no data of its own and
29    is never created - only cast from a ClpInterior object at algorithm time.
30
31    It can also solve QPs
32
33
34
35*/
36
37class ClpPredictorCorrector : public ClpInterior {
38
39public:
40
41     /**@name Description of algorithm */
42     //@{
43     /** Primal Dual Predictor Corrector algorithm
44
45         Method
46
47         Big TODO
48     */
49
50     int solve();
51     //@}
52
53     /**@name Functions used in algorithm */
54     //@{
55     /// findStepLength.
56     //phase  - 0 predictor
57     //         1 corrector
58     //         2 primal dual
59     CoinWorkDouble findStepLength( int phase);
60     /// findDirectionVector.
61     CoinWorkDouble findDirectionVector(const int phase);
62     /// createSolution.  Creates solution from scratch (- code if no memory)
63     int createSolution();
64     /// complementarityGap.  Computes gap
65     //phase 0=as is , 1 = after predictor , 2 after corrector
66     CoinWorkDouble complementarityGap(int & numberComplementarityPairs, int & numberComplementarityItems,
67                                       const int phase);
68     /// setupForSolve.
69     //phase 0=affine , 1 = corrector , 2 = primal-dual
70     void setupForSolve(const int phase);
71     /** Does solve. region1 is for deltaX (columns+rows), region2 for deltaPi (rows) */
72     void solveSystem(CoinWorkDouble * region1, CoinWorkDouble * region2,
73                      const CoinWorkDouble * region1In, const CoinWorkDouble * region2In,
74                      const CoinWorkDouble * saveRegion1, const CoinWorkDouble * saveRegion2,
75                      bool gentleRefine);
76     /// sees if looks plausible change in complementarity
77     bool checkGoodMove(const bool doCorrector, CoinWorkDouble & bestNextGap,
78                        bool allowIncreasingGap);
79     ///:  checks for one step size
80     bool checkGoodMove2(CoinWorkDouble move, CoinWorkDouble & bestNextGap,
81                         bool allowIncreasingGap);