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Re: [Axiom-developer] Units and Dimensions update

From: William Sit
Subject: Re: [Axiom-developer] Units and Dimensions update
Date: Mon, 26 Sep 2005 10:35:44 -0400

Dear Clifford:

C Y wrote:
> The digging continues, and to my surprise there is a considerable body
> of research on these issues.  Just for openers, I've stumbled across
> several lisp implementations of unit/dimensional concepts, a Phd thesis
> on incorporating units/dimensions into programming, and a paper about
> an attempt to teach the formal Z language about units!  Yikes.  

That's in fact a very good development. After all, one always wants to built
upon prior art. Just even reading the first few paragraphs of the thesis already
points out some needed modification to the proposed design: I have assumed that
mostly unit conversions are proportional (I used two fields that are "factors")
so that linear conversion like centigrade to fahrenheit is not immediately
handled without a translation first. And, of course, there are non-linearly
scaled units like decibels, or the Richter scale of earthquakes or the
categories of hurricanes.

> Quite a
> bit of homework to do, so I may fall off the radar screen a bit while I
> try to adsorb at least some of this.  (Plus, my home internet will be
> off for quite a while, so that won't help either.)  If nothing else,
> I'll try to leave a good bibtex file behind to help someone more
> competent than myself.  Never assume anything will be simple!

That's Tim's motto. Quietness before a storm?
> Dr. Sit has been very helpful with his comments, and I wish to thank
> him for his generosity.  

You are welcome, but please just call me "William". I wish to also thank you
since I have learnt quite a bit myself. 

> Definite progress has been made but clearly I
> need to familiarize myself with the work out there on this subject
> before I will be competent to make further revisions.

This is what research is all about and in my opinion, you are very qualified for
this project and your expertise will continue to grow.

Despite having taught unit conversion to some liberal arts students (you can't
expect too much from a text like those) I am also just beginning to learn how to
teach units conversion and to apply that concept to teaching percentage
problems---requiring pecentages carry their reference values as units. So my
point is, one only becomes competent AFTERwards. It's so much easier (to me) to
understand and do the exercises in percentages, where the reference values keep
changing, which now all becomes unit-conversion problems! If I remember, I'll
tell you how this new method fairs after the semester is over.

> In the interests of full disclosure, I should point out the email
> address "smustudent1" is actually no longer correct - I haven't been a
> student at SMU for several years.  The choice was a rather unfortunate
> one - I assumed the Yahoo address would not live beyond my
> undergraduate years.  Oops.  

Please, we are all "Friends of Axiom" (a defunct club that I think participants
from this discussion forum really belong. I would rather not call myself a
developer, since I have not written algebra code for quite a while and have
fallen behind). In this forum, we do not wear our hard hats. So everyone is
welcome as long as they are interested in Axiom (including critizing Axiom).

> I actually have a day job that has nothing
> to do with CASs, so unlike most folks here I'm a hobbyist rather than
> an academic.  I do have a B.S. in Physics, a B.A. in Mathematics, and a
> Masters in Materials Science, but I'm not currently active in academia.

Your background seems to have quite a bit in common with other active

>  While it would be fun to get into this from an academic standpoint I
> doubt the funding would ever be available, or the interest from a
> research standpoint.

Since you have a graduate degree and two undergraduate ones, you are an
academic. Like it or not :-). In the academic world, a lot of research is done
without funding.
> Anyway, just wanted to let y'all know the effort continues!



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