#ifndef __JTOOLS__JHESSEMATRIX__
#define __JTOOLS__JHESSEMATRIX__

#include "JTools/JTable2D.hh"
#include "JTools/JResult.hh"


/**
 * \author mdejong
 */

namespace JTOOLS {}
namespace JPP { using namespace JTOOLS; }

namespace JTOOLS {


  /**
   * Hessian matrix.
   */
  template<unsigned int N, class JData_t = double>
  struct JHesseMatrix :
    public JTable2D<N, N, JData_t>
  {
    /**
     * Default constructor.
     */
    JHesseMatrix()
    {}


    /**
     * Constructor.
     *
     * \param  result          Hesse result
     */
    template<class JResult_t>
    JHesseMatrix(const JResultHesse<JResult_t>& result)
    {
      set(result);
    }


    /**
     * Set matrix according given result.
     *
     * \param  result          Hesse result
     */
    template<class JResult_t>
    void set(const JResultHesse<JResult_t>& result)
    {
      set(0, result);

      for (unsigned int i = 1; i != N; ++i) {
	for (unsigned int j = 0; j != i; ++j) {
	  this->data[i][j] = this->data[j][i];
	}
      }
    }

  private:
    /**
     * Set final element.
     *
     * \param  pivot           pivot
     * \param  result          Hesse result
     */
    void set(unsigned int pivot,
	     const JResultHesse<JData_t>& result)
    {
      this->data[pivot][pivot] = result.fpp;
    }


    /**
     * Set final element.
     *
     * \param  row             row
     * \param  col             col
     * \param  result          Hesse result
     */
    void set(unsigned int row,
	     unsigned int col,
	     const JResultHesse<JData_t>& result)
    {
      this->data[row][col] = result.fp;
    }


    /**
     * Recursivaly set elements.
     *
     * \param  pivot           pivot
     * \param  result          Hesse result
     */
    template<class JResult_t>
    void set(unsigned int pivot,
	     const JResultHesse<JResult_t>& result)
    {
      this->data[pivot][pivot] = get_value(result.fpp);

      set(pivot, pivot + 1, result.fp);
      set(pivot + 1, result.f);
    }


    /**
     * Recursivaly set elements.
     *
     * \param  row             row
     * \param  col             col
     * \param  result          Hesse result
     */
    template<class JResult_t>
    void set(unsigned int row,
	     unsigned int col,
	     const JResultHesse<JResult_t>& result)
    {
      this->data[row][col] = get_value(result.fp);

      set(row, col + 1, result.f);
    }
  };
}

#endif