The dictionary page for / says
(http://www.jsoftware.com/books/help/dictionary/d420.htm):
This definition of insertion over an argument having zero
items extends partitioning identities of the form u/y <->
(u/k{.y) u (u/k}.y) to the cases k e. 0,#y .
"A Programming Language" (1962) also says on page 17:
To complete the system it is essential to define the value of
u/i.0 [Iverson Notation expression translated to J],
the reduction of the null vector of dimension zero, as the
identity element of the operator or relation u .
----- Original Message -----
From: Anssi Seppälä <[EMAIL PROTECTED]>
Date: Sunday, July 9, 2006 9:23 am
Subject: [Jprogramming] Sum of empty vector
> Working with practical statistics and samples that can be also
> empty
> I find that J follows a kind of logic that is uncomfortable.
> Taking
> a empty vector 0$0 (empty sample) :
>
> +/0$0 NB. sum of empty sample is zero !
> 0
>
> (+/ % #) 0$0 NB. mean of empty sample is also zero !
> 0
>
> I wonder why (+/0$0) could not be 0$0 instead of 0 ?
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