//
// $Source: /cvsroot/gambit/gambit/sources/tools/lp/basis.h,v $
// $Date: 2006/01/07 05:41:26 $
// $Revision: 1.3 $
//
// DESCRIPTION:
// Declaration of basis class for tableaus
//
// This file is part of Gambit
// Copyright (c) 2002, The Gambit Project
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//

#ifndef BASIS_H
#define BASIS_H

#include "libgambit/libgambit.h"

//---------------------------------------------------------------------------
// Class Basis
//---------------------------------------------------------------------------

class Basis {

private:
  Gambit::Array<int> basis;        // current members of basis (neg for slacks)
  Gambit::Array<int> cols;         // location of col in basis (0 if not in basis)
  Gambit::Array<int> slacks;       // location of slacks in basis
  Gambit::Array<bool> colBlocked;  
  Gambit::Array<bool> rowBlocked;
  bool IsBasisIdent;

public:
  //-------------------------------------------
  // Constructors, Destructor, Operators
  //-------------------------------------------
  
  Basis(int first, int last, int firstlabel, int lastlabel);
  Basis(const Basis &);
  virtual ~Basis();
  
  Basis& operator=(const Basis&);

  //------------------------------
  // Public Members
  //------------------------------
  
  int First() const;         // First basis index
  int Last() const;          // Last  basis index
  int MinCol() const;    // First Column label
  int MaxCol() const;     // Last Column label

  bool IsRegColumn( int col ) const;
  bool IsSlackColumn( int col ) const; 

  //remove outindex, insert label, return outlabel
  int Pivot(int outindex, int col); 

  // return true iff label is a Basis member
  bool Member(int label) const;

  // finds Basis index corresponding to label number,
  int Find(int label) const;

  // finds label of variable corresponding to Basis index
  int Label(int index) const;

  // marks/unmarks label to block it from entering basis
  void Mark(int label);
  void UnMark(int label);

  // returns true if label is blocked from entering basis
  bool IsBlocked(int label) const;

  // Check if Basis is Ident
  virtual void CheckBasis();
  // returns whether the basis is the identity matrix
  bool IsIdent();
};

#endif // BASIS_H