spline.h

// This file is part of Hermes2D.
//
// Hermes2D 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.
//
// Hermes2D 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 Hermes2D.  If not, see <http://www.gnu.org/licenses/>.

#ifndef __H2D_SPLINE_H
#define __H2D_SPLINE_H

#include "global.h"

namespace Hermes
{
  namespace Hermes2D
  {
    class HERMES_API CubicSpline : public Hermes::Hermes1DFunction<double>
    {
    public:
      CubicSpline(Hermes::vector<double> points, Hermes::vector<double> values,
        double bc_left, double bc_right,
        bool first_der_left = true, bool first_der_right = true,
        bool extend_der_left = true, bool extend_der_right = true);

      CubicSpline(double const_value);

      ~CubicSpline();

      void calculate_coeffs();

      double value(double x) const;

      Hermes::Ord value(Hermes::Ord x) const {return Hermes::Ord(3);};

      double derivative(double x) const;

      Hermes::Ord derivative(Hermes::Ord x) const {return Hermes::Ord(2);};

      void plot(const char* filename, double extension, bool plot_derivative = false, int subdiv = 50) const;

    protected:
      bool find_interval(double x_in, int& m) const;

      double extrapolate_value(double point_end, double value_end, double derivative_end, double x_in) const;
      Hermes::vector<double> points;

      Hermes::vector<double> values;

      double bc_left, bc_right;

      bool first_der_left, first_der_right;
      bool extrapolate_der_left, extrapolate_der_right;

      double point_left, value_left, derivative_left;
      double point_right, value_right, derivative_right;

      Hermes::vector<SplineCoeff> coeffs;

      double get_derivative_from_interval(double x_in, int m) const;

      double get_value_from_interval(double x_in, int m) const;
    };
  }
}
#endif