ConjugateGradient.cpp

/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 
/*
Copyright (C) 2001, 2002, 2003 Nicolas Di Césaré
Copyright (C) 2007 Ferdinando Ametrano
Copyright (C) 2007 Marco Bianchetti
Copyright (C) 2007 François du Vignaud
Copyright (C) 2009 Frédéric Degraeve
 
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.
*/
 
#include "optimization/ConjugateGradient.hpp"
 
#include "optimization/LineSearch.hpp"
#include "optimization/Problem.hpp"
 
namespace QuantLib {
 
  DynamicVector<RealType> ConjugateGradient::getUpdatedDirection(
      const Problem& P, RealType gold2, const DynamicVector<RealType>&) {
    return -lineSearch_->lastGradient() +
           (P.gradientNormValue() / gold2) * lineSearch_->searchDirection();
  }
 
}  // namespace QuantLib