[Development] Etymological digression from QList discussion

Edward Welbourne edward.welbourne at qt.io
Wed Mar 29 11:17:31 CEST 2017

On вторник, 28 марта 2017 г. 01:18:18 EEST Rafael Roquetto wrote:
>> It clearly has nothing to do anymore with the vector from my geometry
>> classes.  I don't know why it received the named 'vector' in first
>> place,

It's "carrier" in Latin; a vector carries several numbers.
Geometry was a late-comer to using vectors.
Physicists studying field theory first developed them,
in the 1800s, starting from the quaternions.

>> but I am willing to bet this is the derivation that some
>> people in linguistics call a 'dead metaphor' (except that the
>> original vector is still alive).

Not sure what you imagine your metaphor was.
You might have a better case for matrix (see below).

Nikita Krupenko (28 March 2017 21:48)
> I think, it came not from the geometr, but from the linear algebra, where
> vector is a m x 1 or 1 x m matrix.
> https://en.wikipedia.org/wiki/Row_and_column_vectors

<sigh /> Well, "matrix" comes from the Latin for mother, rather
indirectly; early industrial revolution metal-working involved stamping
sheets of metal between a matrix and a patrix (from father - I will not
elaborate on the metaphor at work here) to form it into shapes; a matrix
is a pattern establishing a form.  Its usage got diversified from there
and patrix vanished.  Grids of numbers got described using the same word
(the grid is the pattern); but (rank 1) "vectors" were distinguished from
(rank > 1) "matrices" in early linear algebra.  Linear algebra has moved
on from vectors being columns (or rows) of numbers - as I said before,
anything you know how to add to similar things and scale by numbers is a
vector; and this does include linear maps between vector spaces, which
are what matrices represent.  The notation is very convenient, but
seduces some misunderstandings that I'll try not to digress into here ...

Vectors are handy for describing geometry.  Euclidean geometry didn't
use them (it had a well-established notation already) until the notation
was relatively mature; but the theory of smooth manifolds (which is the
world of curved geometry) has little option but to deal with abstract
vectors (as distinct from the columns of numbers that represent them),
covectors (rows) and linear maps (represented by matrices) along with a
whole panoply of co-ordinate-independence analysis.

But I think this is more than enough on the subject of where the word
"vector" comes from; for the purposes of software, a vector is a
sequential collection (with array-like connotations); and the tortuous
path by which that came to be so is beside the point,


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