CardinalBSpline.h

#ifndef UTIL_CARDINAL_B_SPLINE_H
#define UTIL_CARDINAL_B_SPLINE_H

/*
* Util Package - C++ Utilities for Scientific Computation
*
* Copyright 2010 - 2017, The Regents of the University of Minnesota
* Distributed under the terms of the GNU General Public License.
*/

#include <util/containers/DArray.h>    
#include <util/math/Polynomial.h>    
#include <util/math/Rational.h>    
#include <util/global.h>


#include <iostream>

namespace Util
{

   class CardinalBSpline 
   {

   public:



      CardinalBSpline(int degree, bool verbose = false);
     
      ~CardinalBSpline();


      Polynomial<double> const & operator [](int i) const;

      double operator ()(double x) const;

      int degree() const;

   private:

      DArray< Polynomial<double> > floatPolynomials_;

      int degree_;

   };

   /*
   * Get polynomial with real coefficients for domain [i,i+1]
   */
   inline
   Polynomial<double> const & CardinalBSpline::operator [](int i) const
   {  return floatPolynomials_[i]; }

   /*
   * Get value of spline.
   */
   inline
   double CardinalBSpline::operator ()(double x) const
   {  
      if (x <= 0.0) return 0.0;
      int i = x;
      UTIL_ASSERT(i >= 0);
      if (i > degree_) return 0.0;
      return floatPolynomials_[i](x);
   }

   /*
   * Return degree of basis function (i.e., degree of polynomials).
   */
   inline
   int CardinalBSpline::degree() const
   {  return degree_; }

}
#endif