I saw this over on the forum (the diagonalisation takes about twenty
seconds on my MacBookPro with rev enterprise), and two things occur
to me.
'Arrays' in revolution are actually hash tables, so are very nice for
random access to elements, but will not be as efficient for
sequential access as more traditional, fixed width arrays in other
languages.
I suspect that this is the main speed issue with your eigen function.
Secondly, I understand that all numbers in revolution (which is an un-
typed language) are floats - though there may be conversions to and
from integers going on in the engine. I doubt that this will have any
effect on the speed of your functions, but it's probably unneccessary
to write '1.0' or '1.' - simply '1' will do, I think.
I think that using the a[i][j] approach instead of a[i,j] might get
you maybe 10% more speed, but then you'd have to convert to a[i,j]
anyway in order to use the built in matrixmultiply and transpose
functions (this should be updated, I'd have thought).
My maths is nowhere near good enough to suggest mathematical
optimisations (which you might not want for educational purposes,
anyway) and I can't see any obvious optimisations to make in the code
you've written.
Hopefully, someone here will be able to be more helpful, but this may
be one of those things that revolution simply isn't best suited for :(
Best,
Mark Smith
On 27 Aug 2009, at 08:16, Piero Ugliengo wrote:
I am completely new to Revolution. I have downloaded the RevMedia
alpha
version and played a bit with it. I was impressed by how fast I was
able to
port a little VB6 code to RevMedia. This code diagonalizes a symmetric
matrix using the Jacobi algorithm. I checked against the VB6 code
and I got
exactly the same results in the same number of iterations so that
numerics
is the same. However the RevMedia code is at least one order of
magnitude
slower than the VB6 one. For instance a 50x50 matrix is
diagonalized in a
couple of seconds in VB6 and it tooks more than a minute on
RevMedia. I know
that RevMedia is not meant for numerical intensive calculations;
however, I
would like to use it in a scientific teaching context so some power is
needed. I wonder if anybody much expert than me can try the code
using the
most powerful Revolution Studio and if there is a clever way to
deal with
matrix algebra.
The link to download the rev script is here:
http://sites.google.com/site/pierougliengo/download-1/test.rev?
attredirects=0
<http://sites.google.com/site/pierougliengo/download-1/test.rev?
attredirects=0>One
can set the size of the matrix in the onmouse routine.
Thanks a lot
_________________
Piero Ugliengo
--
Prof. Piero Ugliengo
University of Torino
Dip. Chimica IFM, Via P. Giuria, 7 I-10125 Torino
ITALY
Phone: +39-011-670.4596
FAX: +39-011-236.4596
E-mail: piero.uglie...@unito.it
Home page:
http://web086.unito.it/cgi-bin/chimifm/persone.pl/Show?
_id=ugliengo&sort=DEFAULT&search=&hits=70
MOLDRAW: http://www.moldraw.unito.it
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