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From: Hyman Rosen <hyrosen@mail.com>
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Subject: Re: WG: SI Units - has Ada missed the boat?
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Date: Tue, 10 Jul 2007 01:26:08 GMT
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Grein, Christoph (Fa. ESG) wrote:
> I don't know C++ and so I do not know how it deals mit rad, Newton
> Meters and Joule in
> 
> Work [Joule] = Torque [Newton*Meter] * Angle [rad]
> 
> Or sin x = x + x**3/3! + ... where x is in rad, sin x has dimension 1
> (not rad).
> 
> Or Bq = 1/s, Hz = 1/s, but Bq /= Hz.

Here's a description of implementing units using the
Boost Metaprogramming Library.

<http://www.boost.org/libs/mpl/doc/tutorial/dimensional-analysis.html>

I expect that most C++ implementations will follow the rule that
90% of the way is enough, and not bother with radians or trying to
distinguish between becquerel and hertz or Fahrenheit, Celsius, and
Kelvin. But if someone wants to go the whole way, they can do it.
It's just a matter of writing more complicated combining rules for
the templates. And none of it has any runtime overhead at all -
objects of dimensioned types take no more space than plain numbers.