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"Strong typing vs. strong testing"

Keith Thompson kst-u at mib.org
Wed Oct 13 11:24:59 EDT 2010 
RG <rNOSPAMon at flownet.com> writes:
> In article <8hl2ucFdvoU1 at mid.individual.net>,
>  Gregory Ewing <greg.ewing at canterbury.ac.nz> wrote:
>> Tim Bradshaw wrote:
>> > In general any function 
>> > which raises its argument to more than one power ...  doesn't make
>> > much sense if its argument has units.
>> 
>> That's not true. Consider the distance travelled by a
>> falling object: y(t) = y0 + v0*t + 0.5*a*t**2. Here t has
>> dimensions of time, and it's being raised to different
>> powers in different terms. It works because the
>> coefficents have dimensions too, and all the terms end up
>> having the same dimensions.
>
> This reminds me of back when I was a kid and my dad was trying to teach 
> me basic physics.  He kept saying that the acceleration of gravity was 
> 9.8 meters per second squared and I just couldn't wrap my brain around 
> what it meant to square a second.
>
> Now that I think about it, I still can't.  :-)

Fuel economy can be measured in reciprocal acres (or reciprocal
hectares if you prefer).

miles/gallon or km/liter is distance / distance**3 --> distance**-2.

-- 
Keith Thompson (The_Other_Keith) kst-u at mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"
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