Re: [boost] Re: quantity libraries

From: boost (boost_at_[hidden])
Date: 2001-09-05 03:10:22

Salut,

> > TOPIC:  Some "constants" are experimental numbers with finite precision,
> >
> > rather than defined values; they may have to be updated when experiments
> >
> > get better.
> >
> > There seem to be two choices: the values are either compiled-in or
> > read in at run-time.
breaking compatibility of your results.

> There's also a third choice: assume them to have value of 1,
> devise your unit system accordingly, and avoid the whole mess.

a small comment:

working with the strange system where c = h/2pi = 1 has the advantage
that your calculations are independent of measurements of natural constants.
Suppose you want to build a new atominc clock, which is 1000 times more 
precise than older ones, but to convert the result into seconds you
have to apply arithmetic with h. You may now face the problem that your
new device is more accurate than the numerical value of h. therefore
it might be preferable to work in such a system.

Best wishes,
Peter