| // Copyright John Maddock 2007. |
| // Copyright Paul A. Bristow 2010 |
| // Use, modification and distribution are subject to 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) |
| |
| // Note that this file contains quickbook mark-up as well as code |
| // and comments, don't change any of the special comment mark-ups! |
| |
| #include <iostream> |
| using std::cout; using std::endl; |
| |
| // Setting (approximate) precision 25 bits in a single function call using make_policy. |
| |
| //[policy_ref_snip11 |
| |
| #include <boost/math/distributions/normal.hpp> |
| using boost::math::normal_distribution; |
| |
| using namespace boost::math::policies; |
| |
| const int bits = 25; // approximate precision. |
| |
| double q = quantile( |
| normal_distribution<double, policy<digits2<bits> > >(), |
| 0.05); // 5% quantile. |
| |
| //] //[/policy_ref_snip11] |
| |
| int main() |
| { |
| std::streamsize p = 2 + (bits * 30103UL) / 100000UL; |
| // Approximate number of significant decimal digits for 25 bits. |
| cout.precision(p); |
| cout << bits << " binary bits is approoximately equivalent to " << p << " decimal digits " << endl; |
| cout << "quantile(normal_distribution<double, policy<digits2<25> > >(), 0.05 = " |
| << q << endl; // -1.64485 |
| } |
| |
| /* |
| Output: |
| 25 binary bits is approoximately equivalent to 9 decimal digits |
| quantile(normal_distribution<double, policy<digits2<25> > >(), 0.05 = -1.64485363 |
| */ |