[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Emacs-diffs] master 2667d5c: Add new functions for the root mean sq
From: |
David Kastrup |
Subject: |
Re: [Emacs-diffs] master 2667d5c: Add new functions for the root mean square of a (Calc) vector |
Date: |
Wed, 16 Sep 2015 15:46:58 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
Stefan Monnier <address@hidden> writes:
> -*- mode: nit-pick -*-
>
>> +Another commonly used mean, the RMS (root-mean-square), can be computed
>> +for a vector of numbers by using the @kbd{u R}
>
> I must admit that I don't use Calc very often, and read its manual even
> less often, so clearly I'm taking this out of context, but in any case:
>
> To me a "vector" has a rather specific meaning, and taking the root mean
> square of a vector doesn't make much sense. Instead, I like to take the
> rms of a *set* of numbers (which may be provided by packaging them in
> a vector, of course).
Why would you ever want to do that? It may at best make sense for a
finite _multiset_ (which can conveniently be represented by vector
elements). The only difference then is that the members of a multiset
have no order. But once you move to infinite measures as the base, RMS
is still well-defined but you'd rarely want to remove the order by only
viewing cumulative density functions.
At any rate, you could do s/vector of numbers/the numbers in a vector/
but indeed that may suggest that it may not count 1 twice in [1;2;1]
because the "numbers" are just 1 and 2. So one would probably rather do
s/vector of numbers/the vector elements/.
--
David Kastrup