Re: [Boost-bugs] [Boost C++ Libraries] #9966: exponential_distribution returns negative zero

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9966: exponential_distribution returns negative zero
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-02-27 22:11:35

#9966: exponential_distribution returns negative zero
-------------------------------+---------------------------
  Reporter:  mazzamuto@…       |      Owner:  no-maintainer
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  random
   Version:  Boost 1.48.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+---------------------------

Comment (by mazzamuto@…):

 Thanks for your help, I understand what you say on +Inf and about the
 approximation. I must say that I haven't used BOOST extensively, so there
 may be some things that I'm missing. Anyways the problem in the OP did
 cause a bug in a section of my code which wasn't expecting 0 from
 exponential_distribution. I fixed it with an additional check.

 I was referring to this documentation page
 http://www.boost.org/doc/libs/1_57_0/libs/math/doc/html/math_toolkit/dist_ref/dists/exp_dist.html

 where it says: The domain of the random variable is [0, +∞]. Anyways I get
 this output when I ask the range of the distribution. Is the interval open
 or closed? Is it possibile to generate numbers in an open-open interval
 with BOOST? Thanks again.

 {{{
 range of exponential_distribution: 0 inf
 }}}


 {{{#!cpp
 #include <boost/version.hpp>
 #include <boost/math/distributions/exponential.hpp>

 #include <iostream>

 using namespace std;

 int main() {
     cout << "Using BOOST " << BOOST_VERSION << endl;
     cout << "---------------" << endl;

     boost::math::exponential_distribution<double> ed(1);

     pair<double, double> r = boost::math::range(ed);
     cout << "range of exponential_distribution: " << r.first << " " <<
 r.second << endl;

     return 0;
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9966#comment:6>
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