On Wed, Nov 23, 2011 at 9:54 AM, Kai Tietz <[email protected]> wrote:
> 2011/11/23 Ozkan Sezer <[email protected]>:
>> On Tue, Nov 22, 2011 at 11:30 PM, Prof Brian Ripley
>> <[email protected]> wrote:
>>> Assuming you are still updating 1.0, this comes from a bug report on
>>> R built with a toolchain from Sept 2010 (but the bug is still present
>>> in the 1.0 branch).
>>>
>>> Suppose x is what is called in the C code MAXNUM, the maximum
>>> normalized double.  Then pow(x, y) is computed as INF for 0 < y <= 1,
>>> when it should be a perfectly good normalized double. The bug is at
>>> line 382 of pow.c, which has
>>>
>>>         if (x >= MAXNUM)
>>>         {
>>> #if INFINITIES
>>>                 if (y > 0.0)
>>>                         return (INFINITY);
>>> #else
>>>                 if (y > 0.0)
>>>                         return (MAXNUM);
>>> #endif
>>>                 return (0.0);
>>>         }
>>>
>>> It should of course be x > MAXNUM.
>>>
>>> There is a similar problem at line 410, which should be x < -MAXNUM .
>>>
>>> The code in 2.0 and trunk is completely different, and does these
>>> corner cases correctly.
>>>
>>> --
>>> Brian D. Ripley,                  [email protected]
>>> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
>>> University of Oxford,             Tel:  +44 1865 272861 (self)
>>> 1 South Parks Road,                     +44 1865 272866 (PA)
>>> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>>
>> Kai: can you approve that the changes are correct?
>>
>> --
>> O.S.
>
> Hi Ozkan,
>
> Yes, for my understanding of valid value-ranges here, the the check
> should be indeed x > MAXNUM.  Brian is right.  Otherwise we disallow
> the case for MAXNUM.
>
> A patch for this is approved.
>
> Kai
>

Applied rev. 4636
http://mingw-w64.svn.sourceforge.net/viewvc/mingw-w64?view=revision&revision=4636

--
O.S.

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