/* \$Id\$ */ // Copyright (C) 2002, International Business Machines // Corporation and others. All Rights Reserved. // This code is licensed under the terms of the Eclipse Public License (EPL). #ifndef CoinPresolveDoubleton_H #define CoinPresolveDoubleton_H #define DOUBLETON 5 /*! \class doubleton_action \brief Solve ax+by=c for y and substitute y out of the problem. This moves the bounds information for y onto x, making y free and allowing us to substitute it away. \verbatim a x + b y = c l1 <= x <= u1 l2 <= y <= u2 ==> l2 <= (c - a x) / b <= u2 b/-a > 0 ==> (b l2 - c) / -a <= x <= (b u2 - c) / -a b/-a < 0 ==> (b u2 - c) / -a <= x <= (b l2 - c) / -a \endverbatim */ class doubleton_action : public CoinPresolveAction { public: struct action { double clox; double cupx; double costx; double costy; double rlo; double coeffx; double coeffy; double *colel; int icolx; int icoly; int row; int ncolx; int ncoly; }; const int nactions_; const action *const actions_; private: doubleton_action(int nactions, const action *actions, const CoinPresolveAction *next) : CoinPresolveAction(next), nactions_(nactions), actions_(actions) {} public: const char *name() const { return ("doubleton_action"); } static const CoinPresolveAction *presolve(CoinPresolveMatrix *, const CoinPresolveAction *next); void postsolve(CoinPostsolveMatrix *prob) const; virtual ~doubleton_action(); }; #endif