/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ /* Copyright (C) 2000, 2001, 2002, 2003 RiskMap srl This file is part of QuantLib, a free-software/open-source library for financial quantitative analysts and developers - http://quantlib.org/ QuantLib is free software: you can redistribute it and/or modify it under the terms of the QuantLib license. You should have received a copy of the license along with this program; if not, please email <quantlib-dev@lists.sf.net>. The license is also available online at <http://quantlib.org/license.shtml>. This program 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 license for more details. */ /*! \file bisection.hpp \brief bisection 1-D solver */ #ifndef quantlib_solver1d_bisection_h #define quantlib_solver1d_bisection_h #include <ql/math/solver1d.hpp> namespace QuantLib { //! %Bisection 1-D solver /*! \test the correctness of the returned values is tested by checking them against known good results. */ 00035 class Bisection : public Solver1D<Bisection> { public: template <class F> Real solveImpl(const F& f, Real xAccuracy) const { /* The implementation of the algorithm was inspired by Press, Teukolsky, Vetterling, and Flannery, "Numerical Recipes in C", 2nd edition, Cambridge University Press */ Real dx, xMid, fMid; // Orient the search so that f>0 lies at root_+dx if (fxMin_ < 0.0) { dx = xMax_-xMin_; root_ = xMin_; } else { dx = xMin_-xMax_; root_ = xMax_; } while (evaluationNumber_<=maxEvaluations_) { dx /= 2.0; xMid=root_+dx; fMid=f(xMid); evaluationNumber_++; if (fMid <= 0.0) root_=xMid; if (std::fabs(dx) < xAccuracy || fMid == 0.0) { return root_; } } QL_FAIL("maximum number of function evaluations (" << maxEvaluations_ << ") exceeded"); } }; } #endif

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