Scientific computing with D

[Don]

Lars Kyllingstad wrote:
> I think D is, or at least could be, the scientific programming language 
> of the future. Here's why -- and possibly how:
> 
> A couple of years ago, I took a university class called Numerical 
> Physics. After finishing the course, I was left with the impression that 
> numerical computing was all about squeezing every last bit of 
> performance out of the computer -- that unnecessary operations and 
> function calls should be avoided at any cost, even if the resulting code 
> is full of nasty hacks and tricks, making it completely illegible and 
> utterly unmaintainable. And of course, in many cases this is true.
> 
> Now, however, I have a bit more experience in the field and I know that 
> it is not always so. In numerics, as in other areas of programming, it 
> is a trade-off between development time and execution time. 
> Traditionally, if one has a desperate need for speed (sorry), one uses 
> FORTRAN, C or C++. The programs run very fast, but can be hard to 
> develop, debug and maintain. For less processor-intensive tasks one uses 
> Matlab, Mathematica, etc. which have a lot of built-in functionality and 
> make for rapid development, but programs run at a snail's pace.
> 
> With D one has the best of both worlds. I've used both C++ and 
> Mathematica for numerics in the past, but now I use D almost 
> exclusively. I find it a lot easier (and more fun) to code in than C++, 
> and I spend a LOT less time debugging my programs. On the other hand, 
> calculations that would take an entire day in Mathematica are finished 
> in a matter of minutes using D.

I completely agree.

> It's a fact that D programs don't have the performance of C(++) ones, 
> but that, I think, is just a matter of time (pun not intended). It's a 
> relatively new language, and the compilers are still somewhat immature.
> 
> 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.
> 
> Searching dsource, I find that many nice modules and libraries have been 
> made already:
>  - MultiArray (Bill, Fawzi)
>  - dstat (dsimcha)
>  - blip (Fawzi)
>  - MathExtra, BLADE (Don)
>  - Scrapple/backmath (BCS)
>  - Scrapple/units (BCS)
>  - bindings to GSL, BLAS, etc.
>  - ...and probably more
> 
> Myself, I've written/ported some routines for numerical differentiation 
> and integration, one- and multi-dimensional root-finding and some very 
> basic linear algebra, but so far only for personal use. Currently, I'm 
> thinking of porting QUADPACK to D.
> 
> 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.

Yes. I have put all of my completed code into tango.math, and there's a 
fair bit of Fawzi's code in there as well, now. There's a vague plan to 
integrate Bill's stuff eventually, too.

Something that I think is true of all the libraries above, is that 
almost none of the code cares if it is Tango or Phobos. But currently, 
you have to choose, because there's nowhere to put common code.

> Something like the GSL, only written in D. (In my head 
> it's called SciD. At first I thought of DSL - D Scientific Library - but
> that acronym is used all over the place.) I haven't the time, nor the
> skills, to write an entire such library myself, but I'd be happy to 
> contribute where I can.
> 
> Here are some design goals I find important:
>  - sensible, logical and tidy package hierarchy
>  - access to high-level functionality for rapid development
>  - access to low-level functionality for performance
>  - make use of D's awesome compile-time functionality
>  - reusability, pluggability and extensibility
> 
> (By the last point I mean that if one method doesn't work it should be 
> quickly and easily replaceable in code with something else. This is 
> achievable through the use of templates and interfaces, and ties in with 
> the second point.)
> 
> So, what do you think? Am I making any sense? Am I the only one 
> interested in these things?
> 
> All of the above are, of course, my personal opinions. What are yours?

I agree with pretty much everything you've said. I think all that's 
lacking is a bit of organisation. There are quite a lot of scientific 
programmers here, including an impressive number of library developers. 
We could really use a rallying point.

I wonder if it would make sense for Walter to create a NG dedicated to 
scientific programming. digitalmars.D.sci or digitalmars.D.scientific or 
digitalmars.D.math or similar.