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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