The double-quote is the 'rank' conjunction.  In the use here, it means that
the verb applies to rank zero, i.e. scalar, elements of its argument.

Rank is one of the important, general things to understand about J.
Your question about how you would have found this yourself is a good one:
we have talked about this very question repeatedly in our J group here in
New York.  Here's my suggestion based on what we've uncovered about
the J documentation.

Start with the Vocabulary page in the help system if you need to look up
a particular symbol.  Everything about the language is here on one page
though this is both a good and bad thing.  It's good because the compactness
makes it simple to look over the whole thing to find a particular symbol;
it's bad
because the density of information combined with the sparsity of explanation
on
this page can be overwhelming.
However, this page is like a table of contents -
it allows you to find things: explanations are only a click away.

Another very useful thing for a beginner to know about the vocabulary page
is
that very helpful explanatory material immediately precedes it.  Back up
from this
page by clicking on the double 'less-than' symbols "<<" at the top or
bottom.
You'll find about a dozen very helpful, general explanatory pages that set
up
a framework for much of the subsequent documentation.  You could also
start at the beginning of the dictionary by clicking on "Dic" at the top of
the
help page - this will get you to the same general explanations and
eventually
to the Vocabulary page.

Hope this helps.

On 3/30/07, Terrence Brannon <[EMAIL PROTECTED]> wrote:

Part 8/13 of  Lab: An Introductory Course in J has this code:

myverb =: dyad : '2 * x >. y'"0  NB. Create a custom verb: double the
larger'

I would like to know what the double quote mark and zero are doing
after the quoted expression. The tutorial did not explain this.

Some feedback on how I could've discovered this myself is appreciated.
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--
Devon McCormick, CFA
^me^ at acm.
org is my
preferred e-mail
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