Re: Banded matrix storage

I agree. I had something else in mind. Apologies for the confusion.

-----Original Message----- 
From: Nasos Iliopoulos
Sent: Thursday, August 01, 2013 9:31 PM
To: [email protected]
Subject: Re: [ublas] Banded matrix storage

Generally it would not be nice to massively break other codes. So I see
two options:

a) I will either add a BOOST_UBLAS_LEGACY_BANDED #define that will wrap
the old layout scheme, so that people have a way out.

b) Wrap the netlib banded scheme using a BOOST_UBLAS_LAPACK_BANDED
#define and retain the current ublas scheme as the default.

Generally I would prefer a) even if it might surprise some. Any thoughts
or preferences anyone?

Can you also elaborate a little bit on why an all netlib code would
break traits code? I would think it could break code that is
non-agnostic to the storage layout, which is not good either, but I
that  would affect a lot less (if any) codebases.

-Nasos

On 08/01/2013 05:37 PM, [email protected] wrote:
> Naso,
> No problem, just wanted to make sure that I don't do something wrong.
>
> In case it makes sense :
> >From a quick look, it seems to me that one should replace the packed 
> >storage with banded.
> This is in accordance with netlib nomenclature, but I guess would break 
> all shorts (mine included ;) )
> traits code.
>
> ---- Nasos Iliopoulos <[email protected]> wrote:
>> To all:
>> it would be of great help if at least another pair of eyes can review
>> the code before it moves forward into an official release. Here is the
>> github branch:
>>
>> modified test cases (added non square matrices):
>> https://github.com/uBLAS/ublas/blob/ublas_bugfix0002_fix_banded_tc7549/test/test_banded_storage_layout.cpp
>>
>> and modified banded.hpp:
>> https://github.com/uBLAS/ublas/blob/ublas_bugfix0002_fix_banded_tc7549/include/boost/numeric/ublas/banded.hpp
>>
>> relevant lines are 25-56 and and anything that contains the
>> "banded_indexing" specializations.
>>
>> One important change I  made relatively to the old code is that I
>> enabled range checking only in debug builds (where appropriate).
>>
>> Please also note that I didn't follow Gunter's suggestion on adding a
>> new template argument, since I felt it would break backwards
>> compatibility in certain cases.
>> (https://svn.boost.org/trac/boost/ticket/7549)
>>
>>
>> test instructions (not final but they should work):
>> https://github.com/uBLAS/ublas/wiki
>> please do a  git checkout ublas_bugfix0002_fix_banded_tc7549 prior to
>> compiling with b2 otherwise you will be compiling the master branch.
>>
>> I will megre it into ublas_develop after 1-2months so that there is
>> enough time for review and maybe apply some minor modifications I have
>> in mind.
>>
>> On 08/01/2013 01:05 PM, [email protected] wrote:
>>> PS: Although I asked a very-related question, I did not see any answer, 
>>> so I thought it was ignored as
>>> trivial/already answered elsewhere. However, I did receive these very 
>>> relevant emails. Am I doing something wrong ?
>> Petro,
>> Gunter had created some test cases and a bug report on boost trac, so I
>> figured it would help the discussion more to answer to that thread. I
>> restrained myself flooding the mailing list with responses, since yours
>> was just around the corner.
>>
>> Best,
>> Nasos
>>> ---- Rutger ter Borg <[email protected]> wrote:
>>>> On 2013-07-31 17:22, Nasos Iliopoulos wrote:
>>>>> Gunter,
>>>>> I am working on this bug, but based on the test case I am wondering 
>>>>> why
>>>>> should the expected row-major data layout be:
>>>>>
>>>>> 0, 0, 11, 12, 0, 21, 22, 23, 31, 32, 33, 34, 42, 43, 44, 45, 53, 54, 
>>>>> 55, 0
>>>>>
>>>>> And not
>>>>>
>>>>> 0, 12, 23, 34, 45, 11, 22, 33, 44, 55, 21, 32, 43, 54, 0, 31, 42, 53, 
>>>>> 0, 0 ?
>>>>>
>>>>> For the moment I got the column-major implementation working as
>>>>> expected, but I need to add some more tests cases to make sure it is
>>>>> working for non-square matrices as well.
>>>>>
>>>>> Regards,
>>>>>
>>>>> -Nasos
>>>>>
>>>> Hey Nasos,
>>>>
>>>> great work. The data in banded matrices is stored either row-by-row
>>>> (row-major), or column-by-column (column-major). This is defined by
>>>> netlib. AFAIK, a diagonal-by-diagonal storage scheme is not supported 
>>>> by
>>>> CBLAS.
>>>>
>>>> Cheers,
>>>>
>>>> Rutger
>>>>
>>>>
>>>>
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