QuantLib: a free/open-source library for quantitative finance
fully annotated source code - version 1.34
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pathwisediscounter.cpp
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1/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2
3/*
4 Copyright (C) 2008 Mark Joshi
5
6 This file is part of QuantLib, a free-software/open-source library
7 for financial quantitative analysts and developers - http://quantlib.org/
8
9 QuantLib is free software: you can redistribute it and/or modify it
10 under the terms of the QuantLib license. You should have received a
11 copy of the license along with this program; if not, please email
12 <quantlib-dev@lists.sf.net>. The license is also available online at
13 <http://quantlib.org/license.shtml>.
14
15 This program is distributed in the hope that it will be useful, but WITHOUT
16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 FOR A PARTICULAR PURPOSE. See the license for more details.
18*/
21#include <algorithm>
22
23namespace QuantLib
24{
25
27 const std::vector<Time>& rateTimes)
28{
29 checkIncreasingTimes(rateTimes);
30
31 numberRates_ = rateTimes.size()-1;
32 before_ = std::lower_bound(rateTimes.begin(), rateTimes.end(),
33 paymentTime) - rateTimes.begin();
34
35 // handle the case where the payment is in the last
36 // period or after the last period
37 if (before_ > rateTimes.size()-2)
38 before_ = rateTimes.size()-2;
39
40 beforeWeight_=1.0-(paymentTime-rateTimes[before_])/
41 (rateTimes[before_+1]-rateTimes[before_]);
42
44 taus_.resize(numberRates_);
45
46 for (Size i=0; i < numberRates_; ++i)
47 taus_[i] = rateTimes[i+1] - rateTimes[i];
48
49}
50
52 const Matrix& , // LIBORRates, for all steps
53 const Matrix& Discounts, // P(t_0, t_j) for j=0,...n for each step
54 Size currentStep,
55 std::vector<Real>& factors) const
56{
57 Real preDF = Discounts[currentStep][before_];
58 Real postDF = Discounts[currentStep][before_+1];
59
60 for (Size i=before_+1; i<numberRates_; ++i)
61 factors[i+1] =0.0;
62
63 if (postWeight_==0.0)
64 {
65 factors[0] = preDF;
66
67 for (Size i=0; i<before_; ++i)
68 factors[i+1] = -preDF*taus_[i]*Discounts[currentStep][i+1]/Discounts[currentStep][i];
69
70 factors[before_+1]=0.0;
71
72 return;
73 }
74
75 Real df = preDF * std::pow(postDF/preDF, postWeight_);
76
77 factors[0] = df;
78
79 for (Size i=0; i<=before_; ++i)
80 factors[i+1] = -df*taus_[i]*Discounts[currentStep][i+1]/Discounts[currentStep][i];
81
82 factors[before_+1] *= postWeight_;
83}
84}
void getFactors(const Matrix &LIBORRates, const Matrix &Discounts, Size currentStep, std::vector< Real > &factors) const
MarketModelPathwiseDiscounter(Time paymentTime, const std::vector< Time > &rateTimes)
Matrix used in linear algebra.
Definition: matrix.hpp:41
Real Time
continuous quantity with 1-year units
Definition: types.hpp:62
QL_REAL Real
real number
Definition: types.hpp:50
std::size_t Size
size of a container
Definition: types.hpp:58
Definition: any.hpp:35
void checkIncreasingTimes(const std::vector< Time > &times)
check for strictly increasing times, first time greater than zero
Definition: utilities.cpp:92