Re: [ublas] boost numeric bindings lapack gesv + RHEL5 issue.

Subject: Re: [ublas] boost numeric bindings lapack gesv + RHEL5 issue.
From: Sunil Thomas (sgthomas27_at_[hidden])
Date: 2011-09-21 12:01:21

Btw, forgot to mention that in all cases it bails out with INFO=3 (so U(3,3)
is exactly zero
when it fails on Linux).
Thanks,
--Thomas.

On Wed, Sep 21, 2011 at 8:52 AM, Sunil Thomas <sgthomas27_at_[hidden]> wrote:

> Thanks Rutger!
>
>     On Windows I am using Lapack built with IFC, while on Linux, we are
> using already
> existing Lapack libraries (built with fortran compilers g77, I think).. The
> problem is more
> subtle than I thought.. when I build and run my standalong application on
> Windows and
> Linux, it actually runs fine on both. Its only when I am linking my
> application as 3rd party
> libraries to a client application, that it fails on Linux. I forgot to
> mention this fact and for
> that, I apologise. Somehow I think the issue is related to the condition
> number of the
> matrix. Here it is the matrix (9x9) and RHS:
>
> Matrix:
>
> Row #0
> 0.1  4.54773e-010  8.62559e-018  0  0  0  0  0  0
> Row #1
> 0  0  0  0.1  4.54773e-010  8.62559e-018  0  0  0
> Row #2
> 0  0  0  0  0  0  0.1  4.54773e-010  8.62559e-018
> Row #3
> 1.44948e-010  0.166667  -2.61688e-018  0  0  0  0  0  0
> Row #4
> 0  0  0  1.44948e-010  0.166667  -2.61688e-018  0  0  0
> Row #5
> 0  0  0  0  0  0  1.44948e-010  0.166667  -2.61688e-018
> Row #6
> -8.12841e-010  -8.11836e-010  0.0952381  0  0  0  0  0  0
> Row #7
> 0  0  0  -8.12841e-010  -8.11836e-010  0.0952381  0  0  0
> Row #8
> 0  0  0  0  0  0  -8.12841e-010  -8.11836e-010  0.0952381
> RHS:
> 0.1   4.54773e-009   8.62559e-016   1.44948e-010   1.66667
> -2.61688e-016   -8.12841e-010   -8.11836e-009   9.52381
>
> This is just a typical example.. since the matrix/RHS changes
> from iteration to iteration, say. But since all solves fail (when
> they fail on Linux linking to client application), understanding
> this problem should suffice, I think.
>
> Thanks again,
> --Thomas.
>
>
> On Tue, Sep 20, 2011 at 11:40 PM, Rutger ter Borg <rutger_at_[hidden]>wrote:
>
>> On 09/20/2011 11:04 PM, Sunil Thomas wrote:
>>
>>> Hi!
>>>   I am using boost numeric bindings for doing a direct solve using the
>>> lapack function gesv. While this
>>> works great on Windows and gives me the right answer, the exact same
>>> matrix (I printed it out to make
>>> sure) fails on Linux RHEL4 or RHEL5 (returns info=3, zero element on
>>> diagonal). I think the Windows
>>> case was able to pivot it automatically. I am working with some legacy
>>> code here and I see some lines
>>> such as:
>>>
>>>
>> [snip]
>>
>>
>> ()
>>>    It looks like the fix might be something really trivial, but I have
>>> no clue where to look for a hint to resolve
>>> the problem.. appreciate if somebody who's an expert at using boost
>>> ublas can kindly help resolve this
>>> problem.
>>> Thanks a lot for your time,
>>> --S.
>>>
>>
>> In order to help, we need a bit more info on your build environments.
>> I.e., which LAPACK backends are you using, on Windows and on RHEL? Which
>> compilers?
>>
>> Cheers,
>>
>> Rutger
>>
>>
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>

>> Sent to: sgthomas27_at_[hidden]
>>
>
>