akimaspline.h

Go to the documentation of this file.

/*
 * Copyright 2009-2020 The VOTCA Development Team (http://www.votca.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
 
#ifndef VOTCA_TOOLS_AKIMASPLINE_H
#define VOTCA_TOOLS_AKIMASPLINE_H
 
// Standard includes
#include <iostream>
 
// Local VOTCA includes
#include "eigen.h"
#include "floatingpointcomparison.h"
#include "spline.h"
 
namespace votca {
namespace tools {
 
class AkimaSpline : public Spline {
 public:
  // default constructor
  AkimaSpline() = default;
 
  // destructor
  ~AkimaSpline() override = default;
 
  double getSlope(double m1, double m2, double m3, double m4);
 
  // construct an interpolation spline
  // x, y are the the points to construct interpolation, both vectors must be of
  // same size
  void Interpolate(const Eigen::VectorXd &x, const Eigen::VectorXd &y) override;
 
  // fit spline through noisy data
  // x,y are arrays with noisy data, both vectors must be of same size
  void Fit(const Eigen::VectorXd &x, const Eigen::VectorXd &y) override;
 
  // Calculate the function value
  double Calculate(double r) override;
 
  // Calculate the function derivative
  double CalculateDerivative(double r) override;
  using Spline::Calculate;
  using Spline::CalculateDerivative;
 
 protected:
  // p1,p2,p3,p4 and t1,t2 (same identifiers as in Akima paper, page 591)
  Eigen::VectorXd p0;
  Eigen::VectorXd p1;
  Eigen::VectorXd p2;
  Eigen::VectorXd p3;
  Eigen::VectorXd t;
};
 
}  // namespace tools
}  // namespace votca
 
#endif  // VOTCA_TOOLS_AKIMASPLINE_H