[Insight-developers] 0008911: Numerical issues in vnl matrix inversion?

[Bill Lorensen]

Tom,

Sounds good. I'll check in the float-double change in the test and we
can see how things go tonight.

Bill

On Mon, Jul 27, 2009 at 12:46 PM, Tom
Vercauteren<tom.vercauteren at m4x.org> wrote:
> Hi Bill,
>
> To me, both options seems fine. It would be great to have a feedback
> from the bug reporter though.
>
> Then if we choose to change the test and use doubles instead of floats
> we can still use the patch for itk::Matrix if some other machine still
> shows a failing test.
>
> Tom
>
> On Mon, Jul 27, 2009 at 18:29, Bill Lorensen<bill.lorensen at gmail.com> wrote:
>> With your patch, the test passes. However, if I use the original
>> itkMatrix.h code but change the matlab-related matrices to double, the
>> test also passes. Looking at the matlab matrix, I think computing the
>> inverse in double makes sense. Perhaps we should leave itkMatrix alone
>> and fix the test to use double?
>>
>> Bill
>>
>>
>> On Mon, Jul 27, 2009 at 12:00 PM, Bill Lorensen<bill.lorensen at gmail.com> wrote:
>>> I'll try it on my gcc4.3 system.
>>>
>>> On Mon, Jul 27, 2009 at 11:50 AM, Tom
>>> Vercauteren<tom.vercauteren at m4x.org> wrote:
>>>> Hi Bill,
>>>>
>>>> I was actually writing an email about that exact matter :)
>>>>
>>>> A few days ago, I tried to replicate bug 8911
>>>> http://www.itk.org/Bug/view.php?id=8911
>>>>
>>>> I couldn't do it on my machine but since I had the test written, I
>>>> decided to commit it. Now I see it failing on a few machines. So
>>>> apparently, bug 8911 can be replicated.
>>>>
>>>> I agree that letting vxl folks fix it would be good. Another option
>>>> would be to try a fix on ITK's side (which would be faster). I already
>>>> prepared something but cannot currently test whether it works or not.
>>>> The tentative patch is attached here and to the bug tracker. Could you
>>>> try it on your system?
>>>>
>>>> Thanks,
>>>> Tom
>>>>
>>>> On Mon, Jul 27, 2009 at 17:40, Bill Lorensen<bill.lorensen at gmail.com> wrote:
>>>>> Tom,
>>>>>
>>>>> I see that you checked in a test that exhibits the failing inversion.
>>>>> It fails on Borland, gcc 4.3 and MAC 4.0. Does it pass on your system?
>>>>>
>>>>> Is there a plan to fix this? Perhaps we should we let the vxl folks fix it?
>>>>>
>>>>> Bill
>>>>>
>>>>
>>>
>>
>