1234567891011121314151617181920212223242526272829303132333435363738394041424344454647 |
- /* 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;
- }
|