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Date: -- (:)
From: Shivkumar Chandrasekaran <shiv@e...>
Subject: [Caml-list] CamlFloat
I was hoping to hold off on announcing this until the new year..... So 
please take this as just a "pre-announcement".

We plan to release CamlFloat, a "matlab-like" (hopefully better) 
interface to Lapack+Blas "soon". Unfortunately, it is *not* (yet) built 
on top of Lacaml.  It comes with a fully documented interface, a 
tutorial, and a block-sparse matrix module. The code has been 
extensively used in our own research.

For people who cannot wait, they can find a preliminary release here:

http://www.math.ucsb.edu/~lyons/camlFloat/

CleanFloat, a similar package for Clean (http://cs.kun.nl/~clean) will 
also be made available.

--shiv--


On Dec 13, 2003, at 1:38 PM, Oleg Trott wrote:

> On Saturday 13 December 2003 11:36 am, Markus Mottl wrote:
>> On Sat, 13 Dec 2003, romildo@uber.com.br wrote:
>>> I am looking for a good library for numerical
>>> matrixes manipulation in OCaml. Can anybody help me?
>>
>> Although it has already been on the web for a few weeks, I hadn't 
>> actually
>> announced it yet, waiting for comments of some co-developers:
>>
>> Lacaml is available in a new major version. This library interfaces
>> the Fortran libraries BLAS and LAPACK for heavy-weight linear algebra
>> (i.e. matrix computations). New features include support for complex
>> transformations (complex numbers), and a convenient way of accessing
>> submatrices using labels. As usual, you can choose either single or
>> double precision computations. The computations can run in parallel
>> on SMP-machines.
>>
>> You can download the library here:
>>
>>   http://www.oefai.at/~markus/home/ocaml_sources.html#LACAML
>>
>> I'd be grateful for feedback!
>
> All right! I was actually thinking of giving it lately. First of all, 
> I think
> the library is very interesting. Here are some of my assorted thoughts
> regarding improving it.
>
> 1.) I think a matrix library has to have >= 2 levels of 
> user-frienliness. One
> level should be easy to use and have a MATLAB feel to it, i.e. if 
> someone
> wants the eigenvalues of a real matrix, he should just be able to write
>     e_vals = eigenvalues(A)
> or
>    (e_vals, e_vecs) = eigensystem(A)
> without having to worry about details. This should be built on top of a
> low-level interface similar to LAPACK functions themselves. E.g. DGEEV 
> does
> not even return the eigenvectors corresponding to complex eigenvalues, 
> but
> rather something from which they can be reconstructed (which is what
> one might actually want sometimes)
>
> Right now, it appears to me that LaCaml is close to the low level, but 
> not
> quite there (because e.g. some LAPACK interfaces _return_ a matrix 
> rather
> then letting the user modify some piece of memory in place like in 
> FORTRAN)
>
> 2.) Currently, LaCaml interfaces only a fraction of LAPACK. LAPACK is 
> big, and
> interfacing all of it by hand is a huge job. On the other hand, MOST 
> of the
> information needed for the low-level interface can be parsed from 
> function
> declarations in *.f files (I kept thinking about this while using 
> LAPACK in
> my C++ programs). Maybe the way to interface all of LAPACK is
> to parse those *.f files into some intermediate form, let humans edit 
> it (e.g.
> add minimum workspace size expressions, etc. - obvious from docs, but 
> hard to
> parse/NLP), and then auto-generate the whole interface from the 
> result. This
> will have the addtional benefit of being consistent (If you just let a 
> bunch
> of developers contribute interface code directly, they will bring 
> their own
> "style" to their parts of the interface)
>
> 3.) Regarding "WORK" arguments. Why not have a shared workspace:
>
> (* module Workspace, untested *)
>
> (* private *)
> let workspace = ref (Array1.create float64 100)
>
> (* public *)
> let size () = Array1.dim !workspace
>
> let resize n = workspace := Array1.create float64 n
>
> let delete () = resize 0
>
> let get_float64 n = if size () >= n then !workspace
>                                                 else (resize n; 
> !workspace)
>
> This way, one does not need to "hoist" workspace allocation out of 
> loops
> manually. OTOH performance does not suffer from allocating workspace
> for each function call. I don't know how this would inter-operate with
> threading or SMP though.
>
> 4) Submatrices. For a function f that takes a matrix argument "a" of 
> size m by
> n, you normally use something like
>
> f ar ac a m n
>
> where ar and ac refer to the "beginning" of the submatrix. Even though 
> they
> can default to 1, this is kind of inconvenient compared to
>
> f a
>
> I would propose using the latter everywhere, and letting the "mat" type
> include ar, ac, m and n.
>
> submatrix : int -> int -> int -> int -> mat -> mat
> (* submatrix x1 y1 x2 y2 a *)
>
> would provide "views" into matrix a.
>
> 5) I think a function that lets one view matrices as vectors 
> vec_of_mat is
> needed. They are all just ordered sets of numbers after all.
>
> 6) License. Have you thought of adding a static linking exception to 
> your LGPL
> license? Even INRIA did with Caml standard library. I might even 
> consider
> contributing then :-)
>
> -- 
> Oleg Trott <oleg_trott@columbia.edu>
>
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