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Interactive technical computing
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Date: 2007-03-08 (01:49)
From: Jim Miller <gordon.j.miller@g...>
Subject: Re: [Caml-list] Interactive technical computing
I think that this would be a potentially fantastic application!  As a
physicist I am frequently faced with the option of using an interactive tool
that supports graphics (PV-WAVE, IDL, R, and Matlab/Octave are very popular)
but is VERY slow or doing things in a fast but tedious language (C/C++ are
currently the rage with a few individuals that still do Fortran 9X).

Having an OCaml based language that combines a top level command line loop
that allows me to interactive explore data and develop scripts but that
allows me to compile those into something fast could be a very, very useful
tool.  My particular domains are atmospheric photochemistry as well as
satellite mission planning and imagery exploitation.  We tend to do a LOT
less with 3D visualizations and much more with traditional line, contour,
and scatter plots.  We also do a lot of false color imagery.

The closest that I have come to this is a quick module that allows me to
spawn a gnuplot program and pass command strings, via a pipe.  A few
functions to ensure that data is formatted properly and I have something
that's manageable.

I'd be interested in conspiring/planning on something in this space.  It
would also be useful to see if there's a useful way to bridge this with R,
which is my current favorite language for doing statistical data analysis
and plot generation but it still suffers from the problems of speed.

On 3/7/07, Jon Harrop <jon@ffconsultancy.com> wrote:
> Being a user of both OCaml and Mathematica, playing with the new F#
> language
> from Microsoft and watching tutorial videos about VPython:
>   http://showmedo.com/videos/series?name=pythonThompsonVPythonSeries
> has given me a lot of inspiration about interactive technical computing
> environments. This class of applications is hugely useful for working
> scientists and engineers because it lets you slice and dice your data in
> interesting ways whilst also giving you visual throwback and even letting
> you
> do some fancy visualisations.
> For example, I'm in the process of updating my ray tracer language
> comparison:
>   http://www.ffconsultancy.com/languages/ray_tracer/index.html
> and I'm using a mix of OCaml (to fire off compilation and execution
> commands)
> and Mathematica (to dissect the results, compute verbosity using regexps
> and
> plot graphs):
>   http://www.ffconsultancy.com/tmp/mathematica.png
> Mathematica's equivalent of the OCaml top-level is called a notebook. It
> provides expression input and result output, just like OCaml, but
> integrates
> graphics, adds typesetting and lots of mathematical functions. However, it
> is
> widely used for more general purpose programming despite being very slow.
> Using F# from Visual Studio 2005 provides some of this functionality. The
> following screenshots illustrate 2D and 3D graphics spawned from an F#
> interactive session using a little of my own code and
> DirectX/ComponentsXtra:
>   http://www.ffconsultancy.com/tmp/fs_xygraph.png
>   http://www.ffconsultancy.com/tmp/fs_3dplot.png
> For all non-trivials examples in F# it is necessary to spawn a separate
> thread
> to handle the GUI of the visualization, or the GUI will hang when the
> top-level is doing an intensive computation.
> I think F# has a great future because of its ability to spawn
> visualizations
> from a running interactive session. Expensive commercial offerings like
> Matlab and Mathematica are ok when you're doing something they have
> built-in
> (e.g. a Fourier transform) but when you're problem is not trivially
> decomposed into their built-in operators (e.g. a wavelet transform), F#
> and
> OCaml are typically 2-5x faster, and when you must resort to more general
> purpose programming F# and OCaml are often 100x faster.
> However, there is a lot of work to be done in getting competitive charting
> and
> visualization tools into F# and I'm thinking that OCaml could benefit from
> a
> joint venture here. Low-level routines would target DirectX in F# and
> OpenGL
> in OCaml but high-level routines could be language and platform agnostic,
> handling a scene graph that is essentially a typed version of
> Mathematica's
> to provide much faster graphics and even interactive visualisation
> (Mathematica is software rendered and not interactive!).
> This raises several questions:
> . What OCaml programs currently allow OpenGL-based visualizations to be
> spawned from the top-level?
> . Has anyone tried to write an IDE that mixes OCaml code with graphics?
> . Would anyone here be interested in a low-cost cross-platform technical
> computing environment based upon the OCaml and F# languages?
> Obviously I'm interested in this from a commercial perspective. That looks
> easy for F# but not so easy for OCaml. Compiled OCaml+OpenGL code is not
> as
> portable (between machines) as F#+DirectX. Also, I can sell F# DLLs and
> even
> make the library available to other .NET languages (albeit with a
> significantly less productive API).
> Finally, I'd like to note that operator overloading is probably the single
> biggest difference between my F# and OCaml code. The ability to apply +
> and -
> to many types, particularly vectors and matrices, makes this kind of work
> so
> much easier. Even if you have to add the odd type annotation. So I'd love
> to
> see a compatible implementation of overloading introduced into OCaml.
> I'd like to hear everyone's opinions on this as, it seems to me, we're
> sitting
> on the foundations of a great technical computing system.
> --
> Dr Jon D Harrop, Flying Frog Consultancy Ltd.
> OCaml for Scientists
> http://www.ffconsultancy.com/products/ocaml_for_scientists
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