Re: [boost] [Review] Quantitative Units library review begins today March 26

From: Eric Lemings (lemings_at_[hidden])
Date: 2007-03-28 14:12:26

> -----Original Message-----
> From: boost-bounces_at_[hidden] 
> [mailto:boost-bounces_at_[hidden]] On Behalf Of Steven Watanabe
> Sent: Wednesday, March 28, 2007 12:03 PM
> To: boost_at_[hidden]
> Subject: Re: [boost][Review] Quantitative Units library 
> review begins today March 26
> 
> AMDG
> 
> Eric Lemings <lemings <at> roguewave.com> writes:
> 
> > > Allowing conversion between units having different dimensions 
> > > and allowing fundamental units whose dimensions are not 
> > > fundamental e.g. quarts for volume is very very difficult to 
> > > implement.  Off hand, I think that it requires defining some 
> > > special system (probably SI) and converting through that system.
> > 
> > It's not that difficult
> 
> How would you do it?  Using some special set
> of units has problems with extensibility.
> Suppose someone tried to add currency and used
> US dollars as the base and at the same time
> someone else used euros as the base.

Ah sorry.  I misread your initial comment.  I thought you were
referring to units with multiple but same dimensions rather than
units with different dimensions.  In such cases, it's not just very
difficult but is completely impossible according to the rules for
dimensional analysis.

Eric.