Merge commit '4ebe6417a5fce5f0994fc0c31bebf732be96a07c' as 'boost'

boost/libs/numeric/interval/examples/horner.cpp

@@ -0,0 +1,47 @@
+/* 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;
+}