// *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=* // ** Copyright UCAR (c) 1990 - 2016 // ** University Corporation for Atmospheric Research (UCAR) // ** National Center for Atmospheric Research (NCAR) // ** Boulder, Colorado, USA // ** BSD licence applies - redistribution and use in source and binary // ** forms, with or without modification, are permitted provided that // ** the following conditions are met: // ** 1) If the software is modified to produce derivative works, // ** such modified software should be clearly marked, so as not // ** to confuse it with the version available from UCAR. // ** 2) Redistributions of source code must retain the above copyright // ** notice, this list of conditions and the following disclaimer. // ** 3) 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. // ** 4) Neither the name of UCAR nor the names of its contributors, // ** if any, may be used to endorse or promote products derived from // ** this software without specific prior written permission. // ** DISCLAIMER: THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS // ** OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED // ** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. // *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=* /*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*/ // RCS info // $Author: dixon $ // $Locker: $ // $Date: 2016/03/03 18:46:08 $ // $Id: LagrangePtFunc.cc,v 1.7 2016/03/03 18:46:08 dixon Exp $ // $Revision: 1.7 $ // $State: Exp $ /**-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-**/ /********************************************************************* * LagrangePtFunc.cc: class implementing a function defined by a series * of points. The function value for points is * calculated by using Lagrange polynomials. * * RAP, NCAR, Boulder CO * * January 2000 * * Nancy Rehak * *********************************************************************/ #include #include #include #include #include using namespace std; /********************************************************************** * Constructors */ LagrangePtFunc::LagrangePtFunc(map< double, double, less > function) : PtFunction(function) { // Do nothing } /********************************************************************** * Destructor */ LagrangePtFunc::~LagrangePtFunc(void) { } /********************************************************************** * computeFunctionValue() - Compute the function value using linear * interpolation. */ double LagrangePtFunc::computeFunctionValue(const double x) { double l; double p = 0.0; map< double, double, less >::iterator k_iter; map< double, double, less >::iterator i_iter; int k, i; for (k_iter = _function.begin(), k = 0; k_iter != _function.end(); ++k_iter, ++k) { l = 1.0; // Obtain lk(x) for the next term to add to the // interpolating polynomial. for (i_iter = _function.begin(), i = 0; i_iter != _function.end(); ++i_iter, ++i) { if (i != k) l = l * ((x - (*i_iter).first) / ((*k_iter).first - (*i_iter).first)); } // Add the next term computed from lk(x) to the // interpolating polynomial. p = p + ((*k_iter).second * l); } return p; } /********************************************************************** * print() - Print the function information to the given stream. */ void LagrangePtFunc::print(FILE *stream) { fprintf(stream, "Lagrange Polynomial Interpolation Function:\n"); fprintf(stream, "\n"); _printFunction(stream); } void LagrangePtFunc::print(ostream &stream) { stream << "Lagrange Polynomial Interpolation Function:" << endl; stream << endl; _printFunction(stream); } /********************************************************************** * Private Member Functions * **********************************************************************/