[Turning questions around...] On Thu, Jun 09, 2005 at 12:07:54PM +0100, Keean Schupke wrote:
What do people think?
I think this would be cool. One of the things that saddens me about haskell is that I can't really use it for work (or at least, I don't think I could). One thing you haven't mentioned is the ability to create data structures containing matrices and use them nicely (i.e. with operator overloading, etc). This is something that I'd like, so I could create a data type WaveFunction that is an array, but also contains its quantum numbers and other relevant information. In matlab you're stuck with things being a pure matrix, which is highly inconvenient, and that's also the case for most
- is anyone interested in a matrix library?
Yes.
- would people want a library like MatLab where matrices are instances of Num/Fractional/Floating and can be used in normal math equations...
Absolutely. The only annoyance would be that due to haskell's strongly typed approach and lack of automatic type conversions, *everything* would have to be a matrix. That's no worse than matlab, but it's not one of the features of matlib I like. But at least haskell's way of handling rational numbers lends itself to this, since when you make a matrix an instance of Rational (which means defining fromRational), floating point constants can be automatically treated as 1x1 matrices.
- operations like cos/sin/log can be applied to a matrix (and apply to each element like in MatLab)...
Yeah, this does seem necesary. Especially since I envision that *everything* is likely to be a matrix (including scalars). If you could implement even a moderate fraction of octave's functionality (octave being a free matlab clone, for any listeners unfamiliar with it), it would be great. Matlab's got a horrible language, but it's just so darn convenient for dealing with linear algebra. I'd love to be able to recommend that new students learn haskell rather than octave (which I despise). I'm guessing that your simple matrix class doesn't call lapack or do blocked matrix multiplies? A blocked matrix multiply of the fftw/atlas variety would be an interesting project to code in template haskell... -- David Roundy http://www.darcs.net