[Boost-bugs] [Boost C++ Libraries] #7223: ibeta_inv not return 1 correctly when p = 1

Subject: [Boost-bugs] [Boost C++ Libraries] #7223: ibeta_inv not return 1 correctly when p = 1
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-08-10 13:55:35

#7223: ibeta_inv not return 1 correctly when p = 1
-----------------------------------+----------------------------------------
 Reporter:  alex.gilday@…          |        Type:  Bugs            
   Status:  new                    |   Milestone:  To Be Determined
Component:  None                   |     Version:  Boost 1.51.0    
 Severity:  Problem                |    Keywords:                  
-----------------------------------+----------------------------------------
 After porting your ibeta_inv function (and EVERYTHING it requires, ~3000
 lines) to java as part of my work experience, I tested my port against the
 original. I was getting considerably high differences in answers when p =
 1 and q is not given. Your code (and my code) defaults q to 1 - p when not
 given, so 0 in this case. The top of your code also states:

 {{{
    if(q == 0)
    {
       if(py) *py = 0;
       return 1;
    }
 }}}

 This does not happen. It does work in my java code but not in your
 original. There is a rounding error of some sort in 1 - p (or even in p
 alone) that is causing this statement to not evaluate when p is given as 1
 and q is not given.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7223>
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