CubicSpline.h

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//            QMcBeaver
//
//         Constructed by 
//
//     Michael Todd Feldmann 
//              and 
//   David Randall "Chip" Kent IV
//
// Copyright 2000.  All rights reserved.
//
// drkent@users.sourceforge.net mtfeldmann@users.sourceforge.net

#ifndef CubicSpline_H
#define CubicSpline_H

#include <iostream>
#include <string>
#include <math.h>

#include "Array1D.h"
#include "FunctionR1toR1.h"

using namespace std;

class CubicSpline : public FunctionR1toR1
{
public:
  CubicSpline();


  void operator=( const CubicSpline & rhs );


  void initializeWithFunctionValues(const Array1D<double> &xInput, 
                                    const Array1D<double> &yInput, 
                                    double yPrimeFirst, double yPrimeLast);


  void initializeWithDerivativeValues(const Array1D<double> &xInput, 
                                      const Array1D<double> &yPrimeInput, 
                                      double yFirst);

  void evaluate(double x);
  double getFunctionValue();
  double getFirstDerivativeValue();
  double getSecondDerivativeValue();

  double integrate(int indexStart, int indexStop);

  void toXML(ostream& strm);

  friend ostream& operator <<(ostream& strm, CubicSpline & rhs);

protected:
  void evaluate(double x, int index);

private:
  Array1D<double> x_list;      //domain values
  Array1D<double> y_list;      //function values for each x
  Array1D<double> yp_list;     //1st derv of y at each point
  Array1D<double> a0_list;     //poly coeff of f at each point
  Array1D<double> a1_list;     //poly coeff of f at each point
  Array1D<double> a2_list;     //poly coeff of f at each point
  Array1D<double> a3_list;     //poly coeff of f at each point
     
  Array1D<double> row_right;
  Array1D<double> row_middle;
  Array1D<double> row_left;
  Array1D<double> col_rhs;
                  
  double y0;                   //y for smallest x
  double yp0;                  //y prime for smallest x
  double ypend;                //y prime for largest x
  int n;                       //number of input data points;

  double f;
  double dfdx;
  double ddfddx;

  void solve_tridiagonal_system();
  void solve_tridiagonal_system2();
};


#endif

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