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Re: Qhull test changes
From: |
Ben Abbott |
Subject: |
Re: Qhull test changes |
Date: |
Tue, 31 Jan 2012 08:58:58 -0500 |
On Jan 30, 2012, at 9:25 PM, Brad Barber wrote:
> At 08:25 PM 1/30/2012, Ben Abbott wrote:
>
>> On Jan 30, 2012, at 7:42 PM, Brad Barber wrote:
>>
>>> At 07:32 PM 1/30/2012, Ben Abbott wrote:
>>>
>>>> On Jan 30, 2012, at 7:15 PM, Alexander Hansen wrote:
>>>>
>>>>> On 1/30/12 6:02 PM, Rik wrote:
>>>>>
>>>>> <snip>
>>>>>
>>>>>>> I'm not certain, but doesn't "Qt" imply that the convex hull
>>>>>>> should be made up of triangles ? (perhaps I should study the
>>>>>>> qhull docs a bit ?)
>>>>>>>
>>>>>>> In any event, I favored the more recent qhull because it matches
>>>>>>> Matlab's result.
>>>>>>>
>>>>>> Yes, the output should be triangulated when we pass the 'Qt' option
>>>>>> and the new post-2011 Qhull behavior is mathematically correct.
>>>>>> The problem is that Qhull is not returning triangulated output for
>>>>>> versions less than 2011 and users will blame Octave when they see a
>>>>>> failing test in the test report. I am proposing that Octave work
>>>>>> around the different Qhull versions so we don't generate a lot of
>>>>>> spurious bug reports.
>>>>>>
>>>>>> On the other hand, if we want we could leave the test in and also
>>>>>> put in some comments that specifically say, "If you see this test
>>>>>> failing, then you must upgrade your Qhull installation." This
>>>>>> might do a bit towards pushing users and distributions to upgrade
>>>>>> to a new Qhull.
>>>>>>
>>>>>> --Rik
>>>>>
>>>>> Excuse me jumping in, but does this indicate that I should be using
>>>>> qhull>=2011 for my Octave-3.4.3 and Octave-3.6.0 Fink packages? I've
>>>>> been using 2009.3.
>>>>>
>>>>> --
>>>>> Alexander Hansen
>>>>> Fink User Liaison
>>>>
>>>> To use qhull 2011 a patch is needed. 2009, 2010, or 2012 should each be
>>>> ok. The problem appears to be in the tests Octave runs (i.e. make check)
>>>>
>>>> Ben
>>>
>>> I hope that all builds of Octave upgrade to 2012.1. There's a serious bug
>>> with 2009.1 and other bugs fixed in 2011.2 and 2012.1. For details, see
>>> http://gitorious.org/qhull/qhull/blobs/master/src/Changes.txt
>>>
>>> --Brad
>>
>> Is there a simple way to test for the serious 2009 bug ? Something that
>> could be added to the configure process?
>>
>> Ben
>
> Hi Ben,
>
> The easiest is to check the code for qh_gethash in poly.c. It should read
> result %= (unsigned)hashsize;
> Instead of
> hash %= (ptr_intT) hashsize
>
> See http://www.qhull.org/download/poly.c-qh_gethash.patch
>
> The problem occurs if the set elements have the high-bit set. This only
> occurs on 32-bit machines with more than 2G memory. The data needs to be
> allocated in high-mem. Typically, qhull will overwrite an arbitrary location
> with undefined results, often a segfault.
>
> For other notes about bugs see
> http://www.qhull.org/news/qhull-news.html#bugs
>
> --Brad
Do I understand that 2009 can be patched to work properly by making the change
above ? If so, perhaps some linux distributions have done that?
Is it possible to write a simple program that can be used to test if the bug is
present? That would allow us to test for this during the configure process and
give a warning at the end.
Ben
- Re: Release candidate for Qhull 2012.1, (continued)
- Re: Release candidate for Qhull 2012.1, Ben Abbott, 2012/01/30
- RE: Release candidate for Qhull 2012.1, Robinson, Melvin D, 2012/01/30
- Re: Qhull test changes, Rik, 2012/01/30
- Re: Qhull test changes, Ben Abbott, 2012/01/30
- Re: Qhull test changes, Rik, 2012/01/30
- Re: Qhull test changes, Alexander Hansen, 2012/01/30
- Re: Qhull test changes, Ben Abbott, 2012/01/30
- Re: Qhull test changes, Brad Barber, 2012/01/30
- Re: Qhull test changes, Ben Abbott, 2012/01/30
- Re: Qhull test changes, Brad Barber, 2012/01/30
- Re: Qhull test changes,
Ben Abbott <=
- Re: Qhull test changes, Brad Barber, 2012/01/31
- Re: Qhull test changes, Ben Abbott, 2012/01/30
- Re: Qhull test changes, Brad Barber, 2012/01/30
- Re: Qhull test changes, Tatsuro MATSUOKA, 2012/01/30
- Re: Qhull test changes, Tatsuro MATSUOKA, 2012/01/31
- Re: Qhull test changes, Tatsuro MATSUOKA, 2012/01/31
- Re: Qhull include files, Rik, 2012/01/31
- Re: Qhull include files, Brad Barber, 2012/01/31
- Re: Qhull include files, Rik, 2012/01/31