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Re: Getting used to Calc's Radian convention


From: H. Dieter Wilhelm
Subject: Re: Getting used to Calc's Radian convention
Date: Sat, 13 Sep 2014 09:41:01 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.93 (gnu/linux)

address@hidden writes:

>> > Calc's unit convention of revolution per minute (rpm)
>> 
>> > is derived from the angular speed and not from a
>> 
>> > frequency. One does not need to type the factor of `2
>> 
>> > pi' when calculating, for example, the
>> 
>> > circumferential velocity from the radius and some
>> 
>> > value in rpm. So far so good.
>> 
>> >
>> 
>> > But it has the slight aesthetic drawback that now the
>> 
>> > velocity turns out to be in units of radians.
>> 
>> >
>> 
>> > n <- 1 rpm
>> 
>> > r <- 1 m
>> 
>> > n r -> 2 pi rad m / min
>
>
>> My thoughts are: What?!
>
> He's referring to Calc (part of Emacs), which can work with units
> (such as meters, radians, etc.)

Sorry, I made myself not clear and it is basically a question about
physics but there seems to be not separate Calc mailing list.

> Calc doesn't "know" that the rad probably shouldn't be there; perhaps
> there could be a simple way of telling it.

As I said I'm happy with the angular notion of Calc's rpm unit but
it. Maybe it would help to "degrade" Radian -- it is in Calc a base unit
-- to a constant like pi and when converting to base units it simply
vanishes when saying `u b' calc-base-units or an additional unit
function for converting it to its numerical value?

Have fun with Calc
-- 
Best wishes
H. Dieter Wilhelm
Darmstadt, Germany




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