[boost] Re: Physical Quantities revisited

From: Deane Yang (deane_yang_at_[hidden])
Date: 2003-10-22 14:42:10

I believe that a properly designed core dimensions/units library would 
allow for both designs to coexist as higher level libraries.

Paul A. Bristow wrote:

> | -----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]
> 
> 
> 
> _______________________________________________
> Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
>