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#ifndef COSMOINTERFACE_EVOLVERS_RK2NSTORAGEPARAMETERS_H
#define COSMOINTERFACE_EVOLVERS_RK2NSTORAGEPARAMETERS_H
/* File created by Adrien Florio, 2024 */
/* Released under the MIT license, see LICENSE.md. */

#include "CosmoInterface/evolvers/evolvertype.h"

namespace TempLat
{

  // References:
  // - RK3_3:  https://arxiv.org/pdf/2101.05320
  // - RK3_4:  https://ntrs.nasa.gov/api/citations/19940029698/downloads/19940029698.pdf .
  // - RK4_5:  https://arxiv.org/pdf/2101.05320 RK4CK

  template <typename T> class RK2NStorageParameters
  {
  public:
    /* Put public methods here. These should change very little over time. */
    RK2NStorageParameters() = default;

    static std::vector<T> getAs(EvolverType eType)
    {
      std::vector<T> res;

      if (eType == RK2)
        res = {0, -0.5};
      else if (eType == RK3_3)
        res = {0, -5.0 / 9.0, -153.0 / 128.0};
      else if (eType == RK3_4)
        res = {0, -0.7825460361923583, -2.042914325731225, -1.799337253940777};
      else if (eType == RK4_5)
        res = {0, -567301805773.0 / 1357537059087.0, -2404267990393.0 / 2016746695238.0,
               -3550918686646.0 / 2091501179385.0, -1275806237668.0 / 842570457699.0};

      return res;
    }

    static std::vector<T> getBs(EvolverType eType)
    {
      std::vector<T> res;

      if (eType == RK2)
        res = {0.5, 1.0};
      else if (eType == RK3_3)
        res = {1.0 / 3.0, 15.0 / 16.0, 8.0 / 15.0};
      else if (eType == RK3_4)
        res = {0.06688758201974097, 2.876554598956719, 0.5534657361343982, 0.3912730180961791};
      else if (eType == RK4_5)
        res = {1432997174477.0 / 9575080441755.0, 5161836677717.0 / 13612068292357.0, 1720146321549.0 / 2090206949498.0,
               3134564353537.0 / 4481467310338.0, 2277821191437.0 / 14882151754819.0};

      return res;
    }

    static std::vector<T> getCs(EvolverType eType)
    {
      std::vector<T> res;

      if (eType == RK2)
        res = {0.0, 0.5};
      else if (eType == RK3_3)
        res = {0.0, 1.0 / 3.0, 3.0 / 4.0};
      else if (eType == RK3_4)
        res = {0.0, 0.06688758201974097, 0.6924057816719806, 1.0};
      else if (eType == RK4_5)
        res = {0.0, 1432997174477.0 / 9575080441755.0, 0.37040095736420475, 0.6222557631344432, 0.9582821306746903};

      return res;
    }

    static size_t order(EvolverType eType)
    {
      size_t res = 2;
      if (eType == RK3_3) res = 3;
      if (eType == RK3_4) res = 3;
      if (eType == RK4_5) res = 4;
      return res;
    }

    static bool isRK2n(EvolverType ev)
    {
      bool res = false;
      if (ev == RK2 or ev == RK3_3 or ev == RK3_4 or ev == RK4_5) res = true;
      return res;
    }

  private:
    /* Put all member variables and private methods here. These may change arbitrarily. */
  };

} // namespace TempLat

#endif