/*
 Copyright (C) 2001, 2002, 2003 Sadruddin Rejeb

 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 ferdinando@ametrano.net
 The license is also available online at http://quantlib.org/html/license.html

 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 bsmlattice.hpp
    \brief Binomial trees under the BSM model

    \fullpath
    ql/Lattices/%bsmlattice.hpp
*/

// $Id: bsmlattice.hpp,v 1.1.12.1 2002/12/31 18:40:36 nando Exp $

#ifndef quantlib_lattices_bsm_lattice_h
#define quantlib_lattices_bsm_lattice_h

#include <ql/Lattices/lattice.hpp>
#include <ql/Lattices/binomialtree.hpp>

namespace QuantLib {

    namespace Lattices {

        //! Simple binomial lattice approximating the Black-Scholes model
        class BlackScholesLattice : public Lattice {
          public:
            BlackScholesLattice(const Handle<Tree>& tree, 
                                Rate riskFreeRate, 
                                Time end, 
                                Size steps);

            Size size(Size i) const { return tree_->size(i); }
            DiscountFactor discount(Size i, Size j) const { return discount_; }

            const Handle<Tree>& tree() const { return tree_; }
          protected:
            void stepback(Size i, const Array& values, Array& newValues) const;

            Size descendant(Size i, Size index, Size branch) const {
                return tree_->descendant(i, index, branch);
            }
            double probability(Size i, Size index, Size branch) const {
                return tree_->probability(i, index, branch);
            }
          private:
            Handle<Tree> tree_;
            DiscountFactor discount_;
            double pd_, pu_;
        };

        //! Cox-Ross-Rubinstein binomial tree
        class CoxRossRubinstein : public BinomialTree {
          public:
            CoxRossRubinstein(double volatility,
                              Rate riskFreeRate,
                              double underlying,
                              Time end, 
                              Size steps);

            double underlying(Size i, Size index) const;

            double probability(Size i, Size index, Size branch) const;

          private:
            double x0_, sigma_, mu_, dt_;
        };

        //! Jarrow-Rudd binomial tree
        class JarrowRudd : public BinomialTree {
          public:
            JarrowRudd(double volatility,
                       Rate riskFreeRate,
                       double underlying,
                       Time end, 
                       Size steps);

            double underlying(Size i, Size index) const;
            double probability(Size i, Size index, Size branch) const;
          private:
            double x0_, sigma_, mu_, dt_;
        };

    }

}

#endif
