Yes, there should be a period between "x" and "If".
This is now fixed. Thanks for finding and reporting
this error.
Indexing is a function and like all functions the
arguments are arrays. The left argument is an array
of integers in the range from -n to strictly less
than n; the right argument is an array with n items.
For more details on the indexing function { you
can look up its dictionary entry:
http://www.jsoftware.com/help/dictionary/d520.htm
An array keeps a very limited number of its
properties; its being a permutation is not one of
them.
----- Original Message -----
From: Terrence Brannon <[EMAIL PROTECTED]>
Date: Wednesday, March 28, 2007 7:32 am
Subject: [Jgeneral] Questions on Lab: A J Introduction - part 13 Permutations
> If you go to part 13 of the Lab "A J Introduction", you see this:
>
> <quote>
> ── ((1) 13 of 16) Permutations ──────────────────────────────
> The dyadic function x{y indexes y by x If p is a permutation
> p, then p{y permutes y by p.
> )
> </quote>
>
> However, I think there should be a period between "x" and "If"
>
> Also, I find this description confusing. What does it mean to
> index an
> array? Are y and x both arrays?
>
> Is there some tagging of the array created by the
> verb ?. such that J knows the array is a permutation and not just
> an array?
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