From: ptkwt@... (Phil Tomson)
Date: 2005-07-13T11:20:51+09:00
Subject: Re: Design question: use of OO for scientific simulation...

In article <1121208617.962258.82130@g43g2000cwa.googlegroups.com>,
Egg <webb.sprague@gmail.com> wrote:
>Hi all,
>
>I have a slightly embarassingly naive question or set of questions.(I
>am not posting the code because this iteration is in Python--but Ruby
>is next and you all are better OO folks too.)
>
>I am writing a class to do Lee Carter demographic projection of
>mortality (write me if you care about the details): basically involves
>a bunch of 30 x 100 x 18 float matrices, a little linear algebra, and
>some simple monte carlo simulation.
>
>Here are parts of the problem:
>
>* We need to organize storage of a bunch of 3-d matrices and derived
>parameters (which take lots of time to calculate, so want to retain
>them for later).  Various dimensions of the matrices correspond to
>various things, like years of step ahead, age, simulation run, etc, so
>keeping track of that would be good too.  I think this stuff belongs in
>an instance class.
>
>* We have several parameter-finding and simulation-running algorithms,
>taking big matrices and returning big matrices.  I think these should
>be written as functions which don't retain state across calls--then
>they are more testable since they don't require an instantiation of
>anything.
>
>* Each instance needs to display itself in a number of different views
>including graphics and text, often for webservers (so in html), but
>also text for command line use.
>
>* Long term storage, both for command line playing and to put into part
>of a web service (probably run as part of a queue and stored for later
>viewing).
>
>* The basic sequence of interaction is:  1, store some death rates.  2,
>infer some parameters from them.  3, run some simulations.  4, infer
>some more parameters from those simulations.  5, display it all in a
>couple of different ways.
>
>Anyway, I was wondering if anyone has done anything that they liked
>with a situation like this, and could share a pattern or two.  The
>closest design problem might be analysing and simulating genetic
>sequences, if that matters.
>

Sorry, my advice isn't pattern related.  You mention matrices, so I wanted 
to recommend Narray if you haven't already looked at it.  It'll speed 
things up.

Phil