On 2020-08-24 06:46, Lutz Gehlen wrote:

Hi David,thank you for your advice.

YW. :-)

On Sunday, 23.08.2020 06:37:47 David Christensen wrote:On 2020-08-23 02:40, Lutz Gehlen wrote:[...]I am working on a set of modules dealing with banded matrices (aka band matrices or band diagonal matrices). These are a certain kind of sparse matrices where all entries are known to be 0 except close to the main diagonal. Obviously, this condition can be exploited for efficient storage and algorithms.

Follow[ing] the application domain taxonomy names makes the most sense [to me].Hm, that depends on what you consider as the application domain. From an analytical (in a mathematical sense in contrast to numerical) point of view, there is a clear hierarchy. There are general (rectangular) matrices; square matrices are a subset of them, and symmetric matrices are again a subset of square matrices. You might argue that I should use the following namespaces: Math::Matrix::Banded Math::Matrix::Banded::Square Math::Matrix::Banded::Square::Symmetric I suppose that this is what you mean by following the application domain taxonomy or am I wrong? However, from a numerical point of view, the three types are treated rather separately. Specifically, for banded matrices, the three types are stored in different ways and in many cases, you would not apply an algorithm for general square matrices to a symmetric one even if you could, because there are more efficient/stable/etc algorithms at your disposal. Hence, you might rather consider them at the same taxonomic level. This is what I have in mind. One might think of looking at other libraries that implement this kind of software, but they are typically written in C or Fortran and rather tend to very short and cryptic function names like sgbtrf instead of hierarchical namespaces.

`I would favor an analytical mathematics taxonomy over a numerical`

`methods taxonomy or a computer science taxonomy. This should make it`

`easier for users who work in the field to grok the distribution.`

I would add these information architecture considerations;

`- If the term "rectangular matrix" is the general case for all`

`matrices, I would drop "rectangular" and just use "matrix".`

`- If banded is a special case for rectangular matrices, square`

`matrices, and symmetric matrices, I would apply "banded" as a suffix:`

Thus: Math::Matrix::Banded Math::Matrix::Square::Banded Math::Matrix::Square::Symmetric::Banded

`That said, each author could also document their implementation; to`

`allow direct usage and/or optimization by interested users.`

If your implementation is OO and maps 1:1 with the taxonomy, that would be ideal. If not, I might have modules per the taxonomy where it makes sense, and put everything else into sub-directories organized by whatever makes sense for them (such as OO modules, utility functions, whatever).Not sure I understand the second part of your advice. However, my implementation is OO and arguably maps with the taxonomy as discussed above, so it might not be relevant.

`If your OO design does not map 1:1 with the chosen taxonomy, I was`

`suggesting a distribution tree similar to the following:`

Math-Matrix-Banded |-- lib | |-- Math | | |-- Matrix | | | |-- Banded | | | | |-- OO | | | | | |-- <OO implementation tree> | | | | |-- Util.pm | | | | |-- <other stuff as required> | | | | Banded.pm | | | | Square | | | | |-- Banded.pm | | | | |-- Symmetric | | | | | |-- Banded.pm |-- t | |-- <test scripts> |-- MANIFEST |-- Makefile.PL |-- README The lib/Math/Matrix/Banded/OO directory would hold your implementation: - The OO sub-directory would contain your OO implementation. - The file Util.pm would contain whatever non-OO stuff you need. - Other files and directories as needed. The files: - lib/Math/Matrix/Banded.pm - lib/Math/Matrix/Square/Banded.pm - lib/Math/Matrix/Square/Symmetric/Banded.pm

`would provide documentation per the analytical mathematics taxonomy and`

`provide a translation layer from this taxonomy into your OO`

`implementation. Yourself, myself, and any other author(s) would want to`

`collaborate on the translation layer.`

`But, I now see a problem -- the Math::Matrix::Square namespace is not`

`properly contained within the Math-Matrix-Banded distribution.`

`Therefore, Math-Matrix-Square-Banded must be its own distribution.`

`Similarly, Math-Matrix-Square-Symmetric-Banded must be its own`

`distribution. If there is common stuff that can be shared, put it into`

`the first and make the latter two dependent upon the first.`

`The hardest part is planning for the unknown. What name do I use when I`

`create my FBP implementation? These names:`

Math::Matrix::Banded::OO Math::Matrix::Square::Banded::OO Math::Matrix::Square::Symmetric::Banded::OO

`would leave *::FBP for me, *::Structured for the other guy, and`

`*::Quantum for the future.`

You can chase your tail forever when it comes to these kinds of questions...

But if there are other types of banded matrices, if those terms are really at different levels, or if there are other taxonomy issues, perhaps you should release multiple distributions -- one per work product, named per the taxonomy. The idea is that you do not want to block future modules or distributions.Hm, they are the only three choices I foresee, but people might have other ideas. Hence, you have a point. Thinking about this point, I'm also getting second thoughts on using the Math::Matrix namespace to start with. There is a Math::Matrix distribution, does this imply that the entire Math::Matrix namespaceshould be considered "reserved"?

`I would consider CPAN user names to be "reserved". I would not worry`

`about picking a name Math-Matrix-*, so long as it does not collide with`

`any *.pm or *.pod file in any distribution.`

David p.s. I should mention the Polar Bear book [1].

`[1]`

`https://www.oreilly.com/library/view/information-architecture-4th/9781491913529/`