src/m_spline.h

   1 /*$Id: m_spline.h,v 1.1 2009-10-23 12:01:45 felix Exp $ -*- C++ -*-
   2  * Copyright (C) 2001 Albert Davis
   3  * Author: Albert Davis <aldavis@gnu.org>
   4  *
   5  * This file is part of "Gnucap", the Gnu Circuit Analysis Package
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 3, or (at your option)
  10  * any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20  * 02110-1301, USA.
  21  *------------------------------------------------------------------
  22  * piecewise polynomial interpolation
  23  * Constructor args:
  24  * table : a vector of xy pairs, all of the data points.
  25  * d0, dn: boundary conditions -- value of the first derivative at boundaries.
  26  * order : order of interpolating polynomial, must be in {0, 1, 2, 3}.
  27  *
  28  * Outside the range, the result is linearly extrapolated with slope d0, dn.
  29  * ("clamped" splines)
  30  *
  31  * If d0 or dn is set to NOT_INPUT, it is a "natural" spline, with the
  32  * derivative being determined by the data.
  33  * See any numerical analysis text for explanation.
  34  */
  35 //testing=trivial 2006.07.17
  36 #ifndef M_SPLINE_H
  37 #define M_SPLINE_H
  38 #include "u_parameter.h"
  39 /*--------------------------------------------------------------------------*/
  40 struct FPOLY1;
  41 /*--------------------------------------------------------------------------*/
  42 class INTERFACE SPLINE {
  43 private:
  44   int _n;
  45   double* _x;
  46   double* _f0;
  47   double* _f1;
  48   double* _f2;
  49   double* _f3;
  50   int     _order;
  51   double  _d0;
  52
  53   void construct_order_3(double* h, double d0, double dn);
  54   void construct_order_2(double* h, double d0, double dn);
  55   void construct_order_1(double* h, double d0, double dn);
  56 public:
  57   SPLINE(const std::vector<DPAIR>& table,
  58          double d0, double dn, int order);
  59   SPLINE(const std::vector<std::pair<PARAMETER<double>,PARAMETER<double> > >& table,
  60          double d0, double dn, int order);
  61   ~SPLINE();
  62   FPOLY1 at(double x)const;
  63 };
  64 /*--------------------------------------------------------------------------*/
  65 /*--------------------------------------------------------------------------*/
  66 #endif
  67 // vim:ts=8:sw=2:noet: