Scientific computing with D

[Lars Kyllingstad]

Bill Baxter wrote:
> On Fri, Jan 30, 2009 at 10:23 PM, Lars Kyllingstad
> <public at kyllingen.nospamnet> wrote:
>> I think D is, or at least could be, the scientific programming language of
>> the future.
> 
> Agreed!  Numerics is one place where D fits nicely.
> 
>> [...]
>> The one thing I miss the most, however, and which I think is necessary for D
>> to "take off" as a scientific language, is a native D scientific library.
> 
>> I think it would be really nice if many or all of the above mentioned things
>> could be collected in a single library, together with all kinds of other
>> stuff. Something like the GSL, only written in D.
> 
> ...and not GPL, preferably.  :-)
> 
> The goal sounds great.  I'm certainly willing to help out.
> 
> To me it seems one of the first things you need to get nailed down is
> how to represent multidimensional data.  Both dense, strided, and --
> for 2D -- common sparse and BLAS formats.   Probably this can be done
> at the concept (compile-time interface) level without having to go
> into implementation details.  But it might also be nice to have some
> concrete implementation nailed down too, so not everything is built as
> a giant house of template cards.  Once you have that, then any package
> that can work with that concept or array format will be able to share
> data pretty easily.

Agreed. Unfortunately, linear algebra is not my area of expertise. As I 
said, I have written some basic linear algebra code -- very simplistic 
vector/matrix classes, LU decomposition, etc. -- but just because 
they're needed for my numerical calculus modules. I haven't put any work 
into tweaking the performance of this code.

For my use, and I expect for lots of other areas in numerics, very 
simple vector/matrix interfaces suffice. All I need is opIndex, opAdd, 
opSub and opMul. And then you linear algebra people can take care of the 
details. ;) But that's the nice thing about D -- by using templates and 
interfaces, I think it is possible to create a library that's 
user-friendly, but which has super-speedy functions and classes that are 
tailored for very specific use cases.

> But it's not so easy.  Even now I use 3 different libraries at
> different times for different things.
> * I have MatrixT/VectorT,  fixed-size dense matrix and vector, whose
> 2D and 3D versions have some special operations like "cross product"
> * I have Dflat, which provides dynamically-sized Matrix types that
> match what BLAS accepts.  And also a few dynamically-sized sparse
> formats that work with various sparse libs.
> * I have MultiArray which is a generic container for N-dimensional
> strided data, with dynamic number of dimensions and size.
> 
> On the last one ... I consider that one a bit of a failed experiment.
> Dynamic number of dimensions causes too many headaches and is not
> really useful very often.  I think Fawzi is brewing a fix-dim N-d
> array of his own, or was at one point.
> 
> But anyway uniting all these things under a single library or even a
> single concept would be significant work.

...and, I think, would draw even more people to D.

-Lars