spxgeometsc.h

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/*                  This file is part of the class library                   */
/*       SoPlex --- the Sequential object-oriented simPlex.                  */
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/*    Copyright (C) 1996-2012 Konrad-Zuse-Zentrum                            */
/*                            fuer Informationstechnik Berlin                */
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/*  SoPlex is distributed under the terms of the ZIB Academic Licence.       */
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/**@file  spxgeometsc.h
 * @brief LP geometric mean scaling.
 */
#ifndef _SPXGEOMETSC_H_
#define _SPXGEOMETSC_H_

#include <assert.h>

#include "spxdefines.h"
#include "spxscaler.h"

namespace soplex
{
/**@brief Geometric mean row/column scaling.
   @ingroup Algo

   This SPxScaler implementation performs geometric mean scaling of the 
   LPs rows and columns.
*/
class SPxGeometSC : public SPxScaler
{
protected:

   //-------------------------------------
   /**@name Data */
   //@{
   const int  m_maxIterations;    ///< maximum number of scaling iterations.
   const Real m_minImprovement;   ///< improvement nesseccary to carry on.
   const Real m_goodEnoughRatio;  ///< no scaling needed if ratio is less than this.
   //@}

   //-------------------------------------
   /**@name Private helpers */
   //@{
   /// Returns \f$\sqrt{\mbox{mini}\cdot\mbox{maxi}}\f$.
   virtual Real computeScale(Real mini, Real maxi) const;
   //@}

public:

   //-------------------------------------
   /**@name Construction / destruction */
   //@{
   /// default constructor (this scaler makes no use of inherited members m_colFirst and m_doBoth)
   explicit SPxGeometSC(int maxIters = 8, Real minImpr = 0.85, Real goodEnough = 1e3);
   /// copy constructor
   SPxGeometSC(const SPxGeometSC& old);
   /// assignment operator
   SPxGeometSC& operator=(const SPxGeometSC& );
   /// destructor
   virtual ~SPxGeometSC()
   {}
   /// clone function for polymorphism
   inline virtual SPxScaler* clone() const
   {
      return new SPxGeometSC(*this);
   }
   //@}

   //-------------------------------------
   /**@name Scaling */
   //@{
   /// Scale the loaded SPxLP.
   virtual void scale(SPxLP& lp);
   //@}

};
} // namespace soplex
#endif // _SPXGEOMETSC_H_

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