Re: scientific computing with ocaml, gsl api

["David McClain" <dmcclain@azstarnet.com>]

Julian,

I'm not quite sure what you mean by Euclidean N-dimensional algebra, but NML
does already support inner and outer products of N-dimensional objects.
There are also Matrix routines for SVD, Cholesky decomposition, and LU
decomposition, inversion, and determinants, etc...

In fact one of the things I do quite frequently is a DFT demodulation of
image stacks obtained with a chopped sensor. Hence to multiply and sum the
image planes with a twiddle vector I simply do:

    images <*> twiddles

and voila, the result is a single image that represents the sum of
individual weighted images. The "images" vector above is a 3-dimensional
stack of 2-D image planes, while the "twiddles" is a simple vector of scalar
(complex) weights. The "<*>" is shorthand for my inner-product operator.

I am sure that you will easily represent your force problem in the
vectorized domain of NML!

- DM

----- Original Message -----
From: Julian Assange <proff@iq.org>
To: David McClain <dmcclain@azstarnet.com>
Cc: <caml-list@inria.fr>; <proff@iq.org>
Sent: Tuesday, March 28, 2000 11:00 PM
Subject: scientific computing with ocaml, gsl api


> "David McClain" <dmcclain@azstarnet.com> writes:
>
> > Dear OCaml Enthusiasts,
> >
> > It has been stewing for more than a year now, a continuing work in
progress,
> > but it is high time that I release a matured copy of the code and
sources to
> > the world. NML (Not ML, Numeric Modeling Language, Numeric ML, Nearly
ML,
> > ...) is an interactive, dynamically typed, tail pure, compiled (to
native
> > code closures) functional language, whose syntax closely follows that of
> > OCaml, but where all math operations are overloaded and vectorized on
real
> > and complex data in the form of lists, vectors, multidimensional arrays,
> > tuples, etc.
>
> This looks very nice david! Is it possible to use the vectorised, array
support
> within ocaml? i.e I'm a little leary of using NML for mid-large
applications due
> to the lack of type checking, but it does seem to be an excellent language
for
> scientific interrogation.
>
> Have you looked at the GNU scientific library?
>
>         http://sourceware.cygnus.com/gsl
>
> This is a wonderfully eclectic scientific library in C, with strong
> control over float properties. An ocaml or MNL binding would be a
> killer app.
>
>  > Are there any plans to support euclidian vector algebra in n
>  > dimensions? Preferably with user-defined physical field properties?
>  >
>  > Specifically I want to be able to do things like define two vectors,
>  > v_1, and v_2, have v_1 radiate a force decreasing at 1/distance^2, and
>  > calculate the the force vector across all of v_2. This is more complex
>  > than simple point sources, but there doesn't even seem to be support
>  > for those. It could be argued that a two body case is so trivial it
>  > doesn't need supporting, which is probably true, but n body cases and
>  > non point sources are hard work and useful in many (even non-physics)
>  > applications. i.e the v_1, v2 example I mentioned above forms part of
>  > an optimisation solution I have for laying out 2d chemical labels
>  > (part-of-molecule number, atomic weight, charge, etc) over a 3d
>  > polynucleartide in such a way as to avoid the labels writing accross
>  > each other.
>  >
>  > Cheers,
>  > Julian
>