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Re: [Help-gsl] eigen test fails on 32-bit (x86) Linux


From: Victor Zverovich
Subject: Re: [Help-gsl] eigen test fails on 32-bit (x86) Linux
Date: Thu, 11 Aug 2016 20:40:33 +0000

Hi Patrick and others,

While testing GSL 2.1 I've noticed that poly_test has been fixed but
eigen_test is still failing when compiled with -O3 on some platforms:

FAIL: gen, direct eigenvalue(4) imag, random (-0.481216772353650846
observed vs 0.481216772353650846 expected) [877968]
FAIL: gen, direct eigenvalue(5) imag, random (0.481216772353650901 observed
vs -0.481216772353650846 expected) [877970]
FAIL: gen, direct eigenvalue(15) imag, random (6.85872455924790447 observed
vs -6.85872455924790536 expected) [877990]
FAIL: gen, direct eigenvalue(16) imag, random (-6.85872455924790536
observed vs 6.85872455924790625 expected) [877992]

Is it possible to fix eigen_test too e.g. by merging the patch I provided
earlier?

Thanks,
Victor

On Mon, Aug 18, 2014 at 4:11 PM address@hidden <
address@hidden> wrote:

> Indeed, using the version of poly/test.c from the repository fixes the
> issue.
>
> Thanks,
> Victor
>
>
> On Mon, Aug 18, 2014 at 3:06 PM, Patrick Alken <address@hidden
> > wrote:
>
>> This should be fixed on the git repository (see bug #39055), though it
>> may be that the tolerances need adjusting for your system.
>>
>>
>> On 08/18/2014 04:02 PM, address@hidden wrote:
>>
>>> There is another test failure of a similar kind, but now without any -O
>>> flags:
>>>
>>> $ ./configure CFLAGS=
>>> $ make
>>> $ poly/test
>>> FAIL: z1.real, 15th-order polynomial (-0.999999999999994227 observed vs 1
>>> expected) [159]
>>> FAIL: z2.real, 15th-order polynomial (1.00000005616458409 observed vs -1
>>> expected) [161]
>>> FAIL: z13.real, 15th-order polynomial (1.99999988977862886 observed vs 2
>>> expected) [183]
>>> FAIL: z14.real, 15th-order polynomial (2.00000011022135338 observed vs 2
>>> expected) [185]
>>>
>>> Victor
>>>
>>>
>>> On Mon, Aug 18, 2014 at 2:48 PM, address@hidden <
>>> address@hidden> wrote:
>>>
>>> Thanks for quick responses guys.
>>>>
>>>> Patrick, please find attached the patch that implements your suggestion
>>>> which does fix the test failures. I've
>>>> reused GSL_EIGEN_SORT_VAL_{ASC,DESC}, that were previously unused for
>>>> complex numbers, for the new type of comparison.
>>>>
>>>> Victor
>>>>
>>>>
>>>>
>>>> On Mon, Aug 18, 2014 at 12:21 PM, Patrick Alken <
>>>> address@hidden> wrote:
>>>>
>>>> GSL is already sorting the eigenvalues based on magnitude, so the
>>>>> problem
>>>>> seems to be that with the extra -O3 optimization, the gsl_eigen_gen and
>>>>> gsl_eigen_genv routines are producing slightly different results,
>>>>> leading
>>>>> to a different sorting order. One way to fix this would be to sort by
>>>>> real
>>>>> part first and then by imaginary part, but it may be a little while
>>>>> until I
>>>>> can look into this further.
>>>>>
>>>>> Patrick
>>>>>
>>>>>
>>>>> On 08/18/2014 12:59 PM, Martin Jansche wrote:
>>>>>
>>>>> I'm not sure if GSL makes any guarantees about the direction of
>>>>>> eigenvectors. It looks like the test might pass if one only looks at
>>>>>> the
>>>>>> magnitude of the values. Perhaps the test could be made robust against
>>>>>> sign
>>>>>> changes by looking at absolute values.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Aug 18, 2014 at 1:53 PM, address@hidden <
>>>>>> address@hidden> wrote:
>>>>>>
>>>>>>   Hello,
>>>>>>
>>>>>>> I noticed that eigen test fails on 32-bit Linux (x86) when compiled
>>>>>>> with
>>>>>>> -O3 flag:
>>>>>>>
>>>>>>> $ ./configure CFLAGS="-O3"
>>>>>>> $ make
>>>>>>> $ eigen/test
>>>>>>> FAIL: gen, direct eigenvalue(4) imag, random (-0.481216772353650846
>>>>>>> observed vs 0.481216772353650846 expected) [877968]
>>>>>>> FAIL: gen, direct eigenvalue(5) imag, random (0.481216772353650901
>>>>>>> observed
>>>>>>> vs -0.481216772353650846 expected) [877970]
>>>>>>> FAIL: gen, direct eigenvalue(15) imag, random (6.85872455924790447
>>>>>>> observed
>>>>>>> vs -6.85872455924790536 expected) [877990]
>>>>>>> FAIL: gen, direct eigenvalue(16) imag, random (-6.85872455924790536
>>>>>>> observed vs 6.85872455924790625 expected) [877992]
>>>>>>>
>>>>>>> I'm using GSL version 1.16, 32-bit Ubuntu 10.04 and GCC 4.4.3.
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Victor
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>
>>
>


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