damping.h

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/*
 * Copyright (c) 2012-2015:  G-CSC, Goethe University Frankfurt
 * Authors: Andreas Vogel, Christian Wehner
 * 
 * This file is part of UG4.
 * 
 * UG4 is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 3 (as published by the
 * Free Software Foundation) with the following additional attribution
 * requirements (according to LGPL/GPL v3 §7):
 * 
 * (1) The following notice must be displayed in the Appropriate Legal Notices
 * of covered and combined works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (2) The following notice must be displayed at a prominent place in the
 * terminal output of covered works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (3) The following bibliography is recommended for citation and must be
 * preserved in all covered files:
 * "Reiter, S., Vogel, A., Heppner, I., Rupp, M., and Wittum, G. A massively
 *   parallel geometric multigrid solver on hierarchically distributed grids.
 *   Computing and visualization in science 16, 4 (2013), 151-164"
 * "Vogel, A., Reiter, S., Rupp, M., Nägel, A., and Wittum, G. UG4 -- a novel
 *   flexible software system for simulating pde based models on high performance
 *   computers. Computing and visualization in science 16, 4 (2013), 165-179"
 * 
 * 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 Lesser General Public License for more details.
 */
 
#ifndef __H__LIB_ALGEBRA__OPERATOR__DAMPING__
#define __H__LIB_ALGEBRA__OPERATOR__DAMPING__
 
#include "common/common.h"
#include "common/util/smart_pointer.h"
#include "interface/linear_operator.h"
 
namespace ug{
 
template <typename X, typename Y = X>
class IDamping
{
  public:
 
    virtual number damping(const Y& c, const X& d, ConstSmartPtr<ILinearOperator<Y,X> > spLinOp) const = 0;
 
 
    virtual bool constant_damping() const = 0;
 
    virtual number damping() const = 0;
 
    virtual ~IDamping() {}
 
 
    virtual std::string config_string() const = 0;
};
 
template <typename X, typename Y = X>
class ConstantDamping : public IDamping<X,Y>
{
  public:
    ConstantDamping(number factor) : m_factor(factor) {}
 
    virtual number damping(const Y& c, const X& d, ConstSmartPtr<ILinearOperator<Y,X> > spLinOp) const
    {
      return m_factor;
    }
 
    virtual number damping() const
    {
      return m_factor;
    }
 
    virtual bool constant_damping() const {return true;};
 
    virtual std::string config_string() const
    {
      std::stringstream ss; ss << "ConstantDamping(" << m_factor << ")"; return ss.str();
    }
 
  protected:
    number m_factor; 
};
 
template <typename X, typename Y = X>
class MinimalResiduumDamping : public IDamping<X,Y>
{
  public:
    virtual number damping(const Y& c, const X& d, ConstSmartPtr<ILinearOperator<Y,X> > spLinOp) const
    {
      SmartPtr<X> spAc = d.clone_without_values();
      X& Ac = *spAc;
 
      try{
        spLinOp.cast_const()->apply(Ac, c);
      }UG_CATCH_THROW("MinimalResiduumDamping: Computing Ac failed.")
 
    //  Compute scaling
      try{
        const number kappa = VecProd(Ac, d) / VecProd(Ac, Ac);
 
        if (kappa<0.3) return 0.3;
 
      //  return result
        return kappa;
      }UG_CATCH_THROW("MinimalResiduumDamping: Computing (d,Ac)/(Ac,Ac) failed.")
    }
 
    virtual bool constant_damping() const {return false;};
 
    virtual number damping() const
    {
      UG_THROW("MinimalResiduumDamping: non-constant damping.");
    }
 
    virtual std::string config_string() const
    {
      return "MinimalResiduumDamping";
    }
};
 
template <typename X, typename Y = X>
class MinimalEnergyDamping : public IDamping<X,Y>
{
  public:
    virtual number damping(const Y& c, const X& d, ConstSmartPtr<ILinearOperator<Y,X> > spLinOp) const
    {
      SmartPtr<X> spAc = d.clone_without_values();
      X& Ac = *spAc;
      spLinOp.cast_const()->apply(Ac, c);
 
    //  Compute scaling
      const number kappa = VecProd(d,c) / VecProd(Ac, c);
      
      if (kappa<0.3) return 0.3;
 
    //  return result
      return kappa;
    }
 
    virtual bool constant_damping() const {return false;};
 
    virtual number damping() const
    {
      UG_THROW("MinimalEnergyDamping: non-constant damping.");
    }
 
    virtual std::string config_string() const
    {
      return "MinimalEnergyDamping";
    }
};
 
}  // end namespace ug
 
#endif /* __H__LIB_ALGEBRA__OPERATOR__DAMPING__ */