Re: decimal point/comma (was conplaneteering)

On 20 Feb 2005, at 11.19 pm, Mark J. Reed wrote:

> On Sun, Feb 20, 2005 at 04:50:42PM +1100, Tristan McLeay wrote:
>> (Incidentally, you shouldn't really be using - for minus... once we're
>> venturing outside of ASCII, you might as well use the proper minus
>> sign, -. It looks better against + × · ÷ etc.)
>
> Well, in the font I'm using, there's not much difference, but duly
> noted.
>
> And I've never heard of the partial-degree symbol for radians. Of
> course, since radians are a ratio of lengths, they're a unitless
> quantity, so no symbol at all is technically needed, and I've always
> seen it with no units given, letting context tell the story, or with
> the
> word "radians" (usually spelled out, sometimes abbreviated "rad").
Yes; the symbol was instead of rad/'radian' (rad is just the SI symbol
for radians, like g for grams, so it's not technically an abbreviation,
any more than an Omega is an abbreviation for Ohm). However, as you
say, mostly no units were given, and the symbol was really only used in
the first couple of lessons we covered radians, and perhaps in the text
of the textbook which no-one ever read because the teachers made at
least as much sense.

I'm not entirely sure I understand unitless quantities. If radians are
unitless quantities, and I understand that decibels (or rather, bels)
are unitless quantities, does that mean that there should be a
relationship between bels and radians? and so you can say: that angle
is x bels, or: that noise was y radians?

> Besides °/'/", the only other symbolic unit of angle measure I've seen
> is a raised "g" to mean "grad" (a.k.a. "grade", or "gon"; the "metric
> degree" of 0.01 right angle).
I'm under the impression that the closest thing that exists to a metric
degree of angle is radians themselves.

On a tangent led my wild thought processes, I come across a question.
With the conventional measurements of temperature, such as degrees
Celsius and degrees Fahrenheit, you have the modifier after the noun
'degree/s', and the modifier does not change. Colloquially, one can
drop the 'degrees' for scales not commonly used: hence I might talk
about 'thirty-eight degrees' and 'ninety-eight Fahrenheit'. Kelvin, the
proper SI temperature measurement, does not take 'degrees', and looks
like just any other SI measurement. So does one say 'thirty-eight
kelvin' (by analogy with 'ninety-eight Fahrenheit) or 'thirty-eight
kelvins' (by analogy with 'sixty-two metres'), correctly?

--
Tristan.

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