discretization_runge_kutta_alias.hpp

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#ifndef DISCRETIZATION_RUNGE_KUTTA_ALIAS_HPP
#define DISCRETIZATION_RUNGE_KUTTA_ALIAS_HPP

#include <float.h>
#include <memory>
#include <functional>
#include <tuw_control/utils.h>

namespace tuw
{
class StateSim;
using StateSimPtr = std::shared_ptr<StateSim>;

namespace RungeKutta
{
template <std::size_t StateNmSize, std::size_t RKOrder, typename... RKCoeff>
void discretize(StateSim& _stateSim, const double& _arc);
template <>
void discretize<0, 0>(StateSim& _stateSim, const double& _arc);

using DiscretizationFuncPtr = void (*)(StateSim&, const double&);

enum class DiscretizationType
{
  USER_DEF,
  EULER,
  HEUN,
  RK4,
  RK4_38
};

template <std::size_t StateNmSize>
DiscretizationFuncPtr getDiscrFunc(DiscretizationType _discrType)
{
  using Dtp = DiscretizationType;
  switch (_discrType)
  {
    case (Dtp::USER_DEF):
      return discretize<0, 0>;
      break;

    case (Dtp::EULER):
      return discretize<StateNmSize, 1, RatioEval<1, 1> >;
      break;

    case (Dtp::HEUN):
      return discretize<StateNmSize, 2, RatioEval<1, 2>,   // ci  values
                        RatioEval<0, 1>, RatioEval<1, 1>,  // bj  values
                        RatioEval<1, 2>                    // aij values
                        >;
      break;

    case (Dtp::RK4):
      return discretize<StateNmSize, 4, RatioEval<1, 2>, RatioEval<1, 2>, RatioEval<1, 1>,   // ci
                        RatioEval<1, 6>, RatioEval<1, 3>, RatioEval<1, 3>, RatioEval<1, 6>,  // bj
                        RatioEval<1, 2>, RatioEval<0, 1>, RatioEval<1, 2>, RatioEval<0, 1>, RatioEval<0, 1>,
                        RatioEval<1, 1>  // aij
                        >;
      break;

    case (Dtp::RK4_38):
      return discretize<StateNmSize, 4, RatioEval<1, 3>, RatioEval<2, 3>, RatioEval<1, 1>,   // ci
                        RatioEval<1, 8>, RatioEval<3, 8>, RatioEval<3, 8>, RatioEval<1, 8>,  // bj
                        RatioEval<1, 3>, RatioEval<-1, 3>, RatioEval<1, 1>, RatioEval<1, 1>, RatioEval<-1, 1>,
                        RatioEval<1, 1>  // aij
                        >;
      break;
  }
  return nullptr;
}
}
}

#endif  // DISCRETIZATION_RUNGE_KUTTA_ALIAS_HPP