Re: [Axiom-developer] Unit package question - Reply to 1st half

[C Y]

--- William Sit <address@hidden> wrote:

> SI provides standardized prefixes and abbrevations in the range
> 10^(-24) to 10^(24), one for every three unit change in the 
> exponent, which are applicable to ANY physical quantity (with the 
> exception of kilogram, see SI pages, to avoid double prefixes).

Oh, OK!  Well, there goes my most compelling reason to want to be able
to peg individual dimensions to specific units :-).

> More interestingly, SI also has prefixes and abbreviations for
> the computer industry: kilibit (1024 bits) vs kilobit (1000 bits).
> Axiom implementation definitely should adhere to SI standards and 
> implement all their standardized and accepted units.

Agreed.  That could actually be very handy for certain types of
questions about the finer low level points of computer memory :-).
 
> Since SI provides prefixes only for every thousand-fold change, if
> all computations you expect are in the scale of 1 nm, you would
> probably spot these errors in hundreds of nm. But anyway, every 
> scientist should be aware of units attached to quantities, 
> especially in graphs! 

Well, that last argument has got me dead to rights ;-).  Conceded.

> I think autoscaling is good enough (Note, all digital meters 
> autoscales! Scientists are used to that.)

Good point.  Perhaps we could make the autoscaling configurable though,
so people can avoid scaling to less used prefixes unless they so
desire?  (This is so people have the option of only using metric
prefixes they can readily match to some physical standard they are
familiar with, such as a centimeter.)  Usually when the computer tries
to be "smart" like that it is a good idea to allow the user to take
matters into their own hands if they so desire.  (At least, in my
experience - evidently not all software developers agree with me :-/)
 
> I think whoever implements this should first program for the correct
> framework, and provide basic unit systems based on SI. Then as usage
> expands, add more unit system domains. Then if that is not enough,
> add more friendly user settings. I am fairly convinced that the 
> framework proposed earlier is able to handle and
> facilitate this plan of development. I would like to hear more
> critique from others.

So would I - I think I've finally understood the overall arguments now,
and for myself I'm deeply impressed with the insight you have brought
to this problem.  For what it's worth, you have convinced me your
overall direction is the best one to take, and can serve as a good
foundation for tweaks and extensions as desired.
 
> Thanks for this interesting discussion.

Thank you!  This has been an education in and of itself, which I think
is one of the real benefits of a system like Axiom - it forces you to
think deeply about what you are really trying to do.  (Or at least, to
work at understanding others who are up to the deep thinking ;-)

Cheers,
CY


                
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