RE: [boost] Re: Physical Quantities revisited

From: Paul A. Bristow (boost_at_[hidden])
Date: 2003-10-22 13:51:09

| -----Original Message-----
| From: boost-bounces_at_[hidden]
| [mailto:boost-bounces_at_[hidden]]On Behalf Of Andy Little
| Sent: Tuesday, October 21, 2003 2:22 PM
| To: boost_at_[hidden]
| Subject: [boost] Re: Physical Quantities revisited
|
| "Paul A. Bristow" <boost_at_[hidden]> wrote in message
| > I have only expressed a view on one fundamental premise - that all values
| are
| > held internally as SI units - but I may be wrong in this view.
|
| Within SI units there are various units within 1 dimension.
| ie length has units from nanometres to kilometres (and beyond).

I (and others) also expressed the prejudice that all are kept as their base
unit, now that 'everyone' is using at least 64-bit doubles in their calculations
(which is enough to keep everyone except the astronomers in the exponent range.
And the significand precision available (15-ish decimal digits) is ample for all
physical measurements.

Obviously 'everyone' excludes those like toaster designers who must struggle
with much smaller (if any) floating point, ranges and precision.  For them, your
solution is probably best, but for a more general purpose library like Boost, it
may not be preferred.

Hopefully we can find a solution which caters for both.

Paul

Paul A Bristow, Prizet Farmhouse, Kendal, Cumbria, LA8 8AB  UK
[phone]   Mobile [phone]
mailto:pbristow_at_[hidden]