// @(#)root/mathmore:$Id$ // Authors: L. Moneta, A. Zsenei 08/2005 /********************************************************************** * * * Copyright (c) 2004 ROOT Foundation, CERN/PH-SFT * * * * This library is free software; you can redistribute it and/or * * modify it under the terms of the GNU General Public License * * as published by the Free Software Foundation; either version 2 * * of the License, or (at your option) any later version. * * * * This library is distributed in the hope that it will be useful, * * but WITHOUT ANY WARRANTY; without even the implied warranty of * * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * * General Public License for more details. * * * * You should have received a copy of the GNU General Public License * * along with this library (see file COPYING); if not, write * * to the Free Software Foundation, Inc., 59 Temple Place, Suite * * 330, Boston, MA 02111-1307 USA, or contact the author. * * * **********************************************************************/ // Header file for class ChebyshevApprox // // Created by: moneta at Thu Dec 2 14:51:15 2004 // // Last update: Thu Dec 2 14:51:15 2004 // #ifndef ROOT_Math_ChebyshevApprox #define ROOT_Math_ChebyshevApprox /** @defgroup NumAlgo Numerical Algorithms Numerical Algorithm mainly from the \ref MathMore and implemented using the GSL library */ /** @defgroup FuncApprox Function Approximation (ChebyshevApprox) @ingroup NumAlgo */ #ifndef ROOT_Math_IFunctionfwd #include "Math/IFunctionfwd.h" #endif #ifndef ROOT_Math_GSLFunctionAdapter #include "Math/GSLFunctionAdapter.h" #endif #include #include namespace ROOT { namespace Math { class GSLChebSeries; class GSLFunctionWrapper; //____________________________________________________________________________ /** Class describing a Chebyshev series which can be used to approximate a function in a defined range [a,b] using Chebyshev polynomials. It uses the algorithm from GSL This class does not support copying @ingroup FuncApprox */ class ChebyshevApprox { public: /** Construct a Chebyshev series approximation to a Function f in range [a,b]; constructor based on functions of type IGenFunction */ ChebyshevApprox(const ROOT::Math::IGenFunction & f, double a, double b, size_t n); /** Construct a Chebyshev series approximation to a Function f in range [a,b]; constructor based on free functions with gsl_function type signature */ ChebyshevApprox(GSLFuncPointer f, void *p, double a, double b, size_t n); // destructor virtual ~ChebyshevApprox(); private: /** construct a Chebyshev series or order n The series must be initialized from a function */ ChebyshevApprox(size_t n); // usually copying is non trivial, so we make this unaccessible ChebyshevApprox(const ChebyshevApprox &); ChebyshevApprox & operator = (const ChebyshevApprox &); public: /** Evaluate the series at a given point x */ double operator() ( double x) const; /** Evaluate the series at a given point x estimating both the series result and its absolute error. The error estimate is made from the first neglected term in the series. A pair containing result and error is returned */ std::pair EvalErr( double x) const; /** Evaluate the series at a given point, to (at most) the given order n */ double operator() ( double x, size_t n) const; /** evaluate the series at a given point x to the given order n, estimating both the series result and its absolute error. The error estimate is made from the first neglected term in the series. A pair containing result and error is returned */ std::pair EvalErr( double x, size_t n) const; /** Compute the derivative of the series and return a pointer to a new Chebyshev series with the derivatives coefficients. The returned pointer must be managed by the user. */ //TO DO: implement copying to return by value ChebyshevApprox * Deriv(); /** Compute the integral of the series and return a pointer to a new Chebyshev series with the integral coefficients. The lower limit of the integration is the left range value a. The returned pointer must be managed by the user */ //TO DO: implement copying to return by value ChebyshevApprox * Integral(); protected: /** Initialize series passing function and range */ void Initialize( GSLFuncPointer f, void * params, double a, double b); private: size_t fOrder; GSLChebSeries * fSeries; GSLFunctionWrapper * fFunction; // pointer to function }; } // namespace Math } // namespace ROOT #endif /* ROOT_Math_ChebyshevApprox */