MathExp: KISS or All-Out?

[Fawzi Mohamed]

On 2009-10-16 11:13:59 +0200, gzp <galap at freemail.hu> said:

> language_fan írta:
>> Thu, 15 Oct 2009 02:04:09 -0400, Chad J thusly wrote:
>> 
>>> I'm reminded of how annoying it is when there are different libraries
>>> for a language that all define their mathematical types differently and
>>> in incompatible ways (all of the Vec2D, Vec3D, etc ever).  Also
>>> aggravating is when there is one canonical type that everyone uses, but
>>> it is a poor choice (char* in C for strings).
>>> 
>> 
>> Sometimes it feels like Vec3 must be the most reimplemented wheel on the world.
> 
> Yes, i've also started to implement my own matrix/vector library, 
> though could not get too far yet, as I have to learn D meanwhile. I've 
> checked some existing ones (ex. Lyla, and some other on dsource - don't 
> remember the name, sorry), but my main problem was that,
> 
>   - the implementation could not be altered as desired (ex. I need a 
> sparse matrix, where the matrix elements grouped using a quad-tree )
>   - didn't like the coding style ( ex. "_" in function names). In some 
> previous post there was some discussion about this and from my 
> experiences even though we found libraries that has all the capability 
> we required, we did not used them. Sometimes we didn't used our 
> colleagues (good, well-planned) codes either b/c the style differed so 
> much (ex capital letters, "_", m prefix for members etc.) So if a 
> language can enforce a style (at least giving some warnings - and 
> turning on treat warnings as errors :) ), that really helps to reuse 
> codes. Well, it's another topic...
>   - too general where it is not required for me, but could not extend 
> where it is needed for me
>   - seemed to be hard to implement a "general" n-d geometry lib based 
> on   them(ex 2d/3d/nd ray, sphere, plane, etc, simplicals, space 
> partitioning in n-d etc.)
> 
> So it'd be really great to create a "new" d mathematical library, that 
> is developed and discussed by a group.
> 
> Ok, I know there are wrappers for BLAS and other C libraries, but I'd 
> like to see a library written entirely in D.

I think you are greatly underestimating the effort of making "just a 
library for matrixes and vectors"

I think that there are at least 3 areas that have quite different tradeoffs:
* small vectors/matrixes, fixed size
* large dense vector/matrixes
* sparse matrixes/vectors

I did just dense matrixes, in blip, and blas is used if available to 
speed up things when possible (default, use version noBlas noLapack to 
avoid using it), lapack to implement more complex linear algebra stuff.

For sparse matrixes Bill has hidden them in the multiarray project, the 
multiarray implementation there is quite slow and has some 
shortcomings, but it hasn't been the focus of bill since a long time.
But he has wrappers for sparse matrixes, and several sparse matrix libs 
that he actively uses.

for small vectors/matrixes I use open math for games (omg) implementation.

ciao
Fawzi