[Bug libstdc++/40331] New: uniform_real random number distribution produces wildly out of range values (TR1 & C++0x)

[Bug libstdc++/40331] New: uniform_real random number distribution produces wildly out of range values (TR1 & C++0x)

[colin at gibibit dot com]

Using either the std::tr1 or C++0x std:: random number generators, the
uniform_real distribution produces numbers that are completely wrong.

For instance, using Boost.Random the test program produces this sequence of
floating point numbers:

Random real: 0.0975404
Random real: 0.547221
Random real: 0.278498
...

On the other hand, both the TR1 and C++0x random number generators produce
something like

Random real: 4.18933e+08
Random real: 2.35029e+09
Random real: 1.19614e+09
...

instead.

This is using the mt19937 random number generator engine and the uniform_real
distribution.  I have tried both uniform_real<float> and uniform_real<double>
and they both have this bug.


-- 
           Summary: uniform_real random number distribution produces wildly
                    out of range values (TR1 & C++0x)
           Product: gcc
           Version: 4.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: colin at gibibit dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40331

[Bug libstdc++/40331] uniform_real random number distribution produces wildly out of range values (TR1 & C++0x)

[colin at gibibit dot com]

------- Comment #1 from colin at gibibit dot com  2009-06-03 15:52 -------
Created an attachment (id=17948)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17948&action=view)
Test case that generates random reals using Boost, TR1, and C++0x

Uncomment exactly one of RNG_BOOST, RNG_TR1, or RNG_CXX0X to select the random
number generator implementation to use.  Only the Boost random number generator
produces values from uniform_real in the correct range.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40331

[Bug libstdc++/40331] uniform_real random number distribution produces wildly out of range values (TR1 & C++0x)

[paolo dot carlini at oracle dot com]

------- Comment #2 from paolo dot carlini at oracle dot com  2009-06-03 16:49 -------


*** This bug has been marked as a duplicate of 40263 ***


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40331