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 15:48:58

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

 Replying to [comment:4 mazzamuto@…]:
 > I agree that the problem is not with the sign. Indeed I recognize that
 the documentation states: The domain of the random variable is [0, +Inf].

 Which documentation?  I don't see any such statement in
 the Boost.Random docs.

 > This causes another problem with the upper limit +Inf being documented
 as included. For example, this code should produce the minimum and maximum
 values obtainable from exponential_distribution with lambda=1:

 An exponential_distribution should never produce +Inf.  Theoretically,
 lim_{x->\inf} p(x) = 0, so while the values can be arbitrarily large, the
 distribution should never produce infinity.  We have to approximate the
 distribution, because floating point cannot represent every real number,
 but adding +Inf as a possible output would severely bias the distribution
 (i.e. the mean would become +Inf).  I can't think of any circumstances
 where I would want it to return +Inf.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9966#comment:5>
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