RE: [boost] Quantity library: any interest?

From: Paul A. Bristow (boost_at_[hidden])
Date: 2003-04-16 15:37:42

> -----Original Message-----

> [mailto:boost-bounces_at_[hidden]] On Behalf Of renej_at_[hidden]
> Sent: Wednesday, April 16, 2003 9:29 AM
> To: boost_at_[hidden]
> Subject: RE: [boost] Quantity library: any interest?

> > Perhaps we need more real user experience.

> real user experience... you asked for it ;-)
> we use the int-based template approach for a couple of years now in
> our AGV controller software. We actually sometimes reach the stage that
> it works when succesfully compiled and linked. Since our control software
> is physics throughout (field of robotics), the type safety is very
> important. However, besides the basic SI units we also have 'angle'
> as a dimension which allows us to distinguish 'velocity' and 'angular
> velocity' for example. Hence, from out 'real user' experience (engineering
> point of view) it would be a necessity to add 'angle' as a dimension
> without breaking already defined quantities. Most (all?) units libraries
> already define 'angle' to be dimensionless, which is true in scientifically
> spoken, but pragmatically (engineering ;-) less handy.

This is really encouraging, and shows the value of comparing theory with
practice.

Aside: "In theory, there is no difference between theory and practice.
But in practice, there's no similarity." Jan L A van de Snepscheut

> > I also feel strongly that users need to be able to handle 'uncertainty
> > of quantity' by combining Quantity/SIUnits with the interval library
> > (and something built on top of the interval library to include more
> > information about 'uncertainty of uncertainty' clues like degrees of
> > freedom). So I wonder if either or both fit together?
>
> as an example, for the variables representing degrees of freedom of
> the rigid body (AGV in our case), we have additional accuracy and
> reliability variables. When those could make use of SI-based interval
> valued variables, that would be indeed nice.

> I'd like to stress that to
> be usefull for a broader audience, one should be able to use it in parts ...

> for what it's worth,
> renej

Really worthwhile feedback - shows that Units would be a useful Boost Brick.

Paul

Paul A Bristow, Prizet Farmhouse, Kendal, Cumbria, LA8 8AB  UK
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