Dimensional analysis doesn't deal with the F and C temperature scales
(though it can deal with F and C temperature *differences*). Only the K
scale makes sense.
ezunits does handle degC and degF in simple cases, e.g. 0 ` degC `` degF,
but you can easily construct meaningless things like 1 ` degC*m.
So I am OK with a units framework which doesn't handle such things.
-s
On Thu, Nov 1, 2012 at 10:44 AM, Rupert Swarbrick <rswarbrick at gmail.com>wrote:
> Stavros Macrakis <macrakis at alum.mit.edu> writes:
> > I believe that multiplication/division is logically a reasonable
> operation
> > for units, with the right algebraic properties, e.g. (a+b)*unit ==
> a*unit +
> > b*unit; unit1*unit2 == unit2*unit1; etc.
>
> Robert didn't answer this bit, so I'll point out one problem: Not all
> units are scalar multiples of other units for the same quantity. For
> example, centigrade and farenheight are not related linearly, but affine
> linearly.
>
> I'm pretty certain I remember my mother (a physics teacher) explaining
> this to me when I was younger because was asking why we bothered with
> units at all ("after all, can't you just pretend kg is a number?").
>
> Rupert
>
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