| /* Boost example/horner.cpp |
| * example of unprotecting rounding for a whole function computation |
| * |
| * Copyright 2002-2003 Guillaume Melquiond |
| * |
| * Distributed under the Boost Software License, Version 1.0. |
| * (See accompanying file LICENSE_1_0.txt or |
| * copy at http://www.boost.org/LICENSE_1_0.txt) |
| */ |
| |
| #include <boost/numeric/interval.hpp> |
| #include <iostream> |
| |
| // I is an interval class, the polynom is a simple array |
| template<class I> |
| I horner(const I& x, const I p[], int n) { |
| |
| // initialize and restore the rounding mode |
| typename I::traits_type::rounding rnd; |
| |
| // define the unprotected version of the interval type |
| typedef typename boost::numeric::interval_lib::unprotect<I>::type R; |
| |
| const R& a = x; |
| R y = p[n - 1]; |
| for(int i = n - 2; i >= 0; i--) { |
| y = y * a + (const R&)(p[i]); |
| } |
| return y; |
| |
| // restore the rounding mode with the destruction of rnd |
| } |
| |
| template<class T, class Policies> |
| std::ostream &operator<<(std::ostream &os, |
| const boost::numeric::interval<T, Policies> &x) { |
| os << "[" << x.lower() << ", " << x.upper() << "]"; |
| return os; |
| } |
| |
| int main() { |
| typedef boost::numeric::interval<double> I; |
| I p[3] = { -1.0, 0, 1.0 }; |
| I x = 1.0; |
| std::cout << horner(x, p, 3) << std::endl; |
| return 0; |
| } |