/*********************************************************************
 *
 * Software License Agreement (BSD License)
 *
 *  Copyright (c) 2012, Scott Niekum
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
 *     copyright notice, this list of conditions and the following
 *     disclaimer in the documentation and/or other materials provided
 *     with the distribution.
 *   * Neither the name of Willow Garage nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 *  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 *
 *********************************************************************/

/**
  * \author Scott Niekum
  */

#ifndef FOURIER_APPROX_H_
#define FOURIER_APPROX_H_

#include "lwr_seed_control/DMP/function_approx.h"
#include <iostream>
#include <Eigen/Core>
#include <Eigen/SVD>
#include <Eigen/LU>

namespace  DMP_RosWrapper{

/// Class for linear function approximation with the univariate Fourier basis
class FourierApprox : public FunctionApprox{
public:
	FourierApprox(int order);
	FourierApprox(const std::vector<double> &w);
	virtual ~FourierApprox();

	/**\brief Evaluate the function approximator at point x
	 * \param x The point at which to evaluate
	 * \return The scalar value of the function at x
	 */
	virtual double evalAt(double x);

	/**\brief Computes the least squares weights given a set of data points
	 * \param X A vector of the domain values of the points
	 * \param Y A vector of the target values of the points
	 */
	virtual void leastSquaresWeights(double *X, double *Y, int n_pts);

private:
	/**\brief Calculate the Fourier basis features at point x
	 * \param x The point at which to get features
	 */
	void calcFeatures(double x);

	/**\brief Calculate the Moore-Penrose pseudoinverse of a matrix using SVD
	 * \param mat The matrix to pseudoinvert
	 * \return The pseudoinverted matrix
	 */
	Eigen::MatrixXd pseudoinverse(Eigen::MatrixXd mat);

	double *features;  //Storage for a set of features

};

}

#endif /* FOURIER_APPROX_H_ */
