The J dictionary uses "atom" and "scalar" 
synonymously, much like "verb" and "function", and
does not distinguish atom and scalar in the way
described in the appended msg.  Section II A
http://www.jsoftware.com/help/dictionary/dicta.htm
says:
   Arrays of ranks 0, 1, and 2 are also called
   _atom_, _list_, and _table_, or, in math,
   _scalar_, _vector_, and _matrix_.

One can read too much into the meaning of the word
"atom" (indivisible).  In the immediately following
paragraph, it says:
   A single entity such as 2.3 or _2.3j5 or
   'A' or '+' is called an atom.
An entity such as _2.3j5 or even 2.3 _is_ divisible
if you change the terms of reference.  In J, atom
(or scalar) just means rank-0 array.

Regarding the monad <y, the dictionary page for <
http://www.jsoftware.com/help/dictionary/d010.htm
says that 
   <y is an _atomic encoding_ of y , ...



----- Original Message -----
From: Dan Bron <[EMAIL PROTECTED]>
Date: Thursday, April 5, 2007 7:36 am
Subject: Re: [Jgeneral] Need a word for a non-atomic array

> I would also like to emphasize a distinction that no one has draw 
> in recent discussions:
> 
>   A scalar is a rank zero array.
>   An atom is an open scalar.
> 
> That, is: an atom is fundamental.  Indivisible.  A building block. 
> It has no structure; hence, no structural changes can be made to 
> it.  The monad  <  produces  _scalars_, not atoms.  To be precise:
> 
> 
>     scalar  =:  '' -: $
>     atom    =:  scalar *. 0 -: L.    NB.  Or  scalar *. (-: >)
> 
> 
> -Dan
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