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/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
Copyright (C) 2003 Ferdinando Ametrano
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.
*/
// ===========================================================================
// NOTE: The following copyright notice applies to the original code,
//
// Copyright (C) 2002 Peter Jäckel "Monte Carlo Methods in Finance".
// All rights reserved.
//
// Permission to use, copy, modify, and distribute this software is freely
// granted, provided that this notice is preserved.
// ===========================================================================
#include <ql/math/primenumbers.hpp>
#include <iterator>
namespace QuantLib {
namespace {
const BigNatural firstPrimes[] = {
// the first two primes are mandatory for bootstrapping
2, 3,
// optional additional precomputed primes
5, 7, 11, 13, 17, 19, 23, 29,
31, 37, 41, 43, 47 };
}
std::vector<BigNatural> PrimeNumbers::primeNumbers_;
BigNatural PrimeNumbers::get(Size absoluteIndex) {
if (primeNumbers_.empty()) {
Size n = sizeof(firstPrimes)/sizeof(firstPrimes[0]);
primeNumbers_.insert(primeNumbers_.end(),
firstPrimes, firstPrimes+n);
}
while (primeNumbers_.size()<=absoluteIndex)
nextPrimeNumber();
return primeNumbers_[absoluteIndex];
}
BigNatural PrimeNumbers::nextPrimeNumber() {
BigNatural p, n, m = primeNumbers_.back();
do {
// skip the even numbers
m += 2;
n = static_cast<BigNatural>(std::sqrt(Real(m)));
// i=1 since the even numbers have already been skipped
Size i = 1;
do {
p = primeNumbers_[i];
++i;
} while (((m % p) != 0U) && p <= n);
} while ( p<=n );
primeNumbers_.push_back(m);
return m;
}
}
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