[Jprogramming] @: and capped fork

[Ric Sherlock]

You can alter the display like you could in j602 by setting the noun
DisplayForm in the base.cfg file. You can access it from the jgtk menu using
Edit|Configure|Base

As others have described in this thread, beginners come in many different
shapes & sizes which makes it pretty hard to come up with the "right" set
of tools for beginners. I know for example that it took me at least 18
months before I really started to understand tacit. I was happy and
productive without it. For others tacit J is why they're drawn to the
language.

Here's one relatively understandable way of defining the cosine rule that
might work for beginners.

require 'trig'
NB.*cosrule v Uses cosine rule to calc missing angle/side
NB. monadic result: length of missing side
NB. dyadic result: size of missing angle
NB. y is: lengths of known sides
NB. x is: size of angle opposite unknown side
NB. eg: cosrule 4.2 6.9 4
NB. eg: 31.8183 cosrule 4.2 6.9
cosrule=: 3 : 0
  'a b c'=. 3 {. y
  dfr arccos ((+/ *: a,b) - *:c) % 2*a*b
:
  'a b'=. 2 {. y
  C=. rfd x
  %: (+/ *: a,b) - 2*a*b*cos C
)



On Sun, Dec 2, 2012 at 12:15 AM, Alex Giannakopoulos <
aegean at blueyonder.co.uk> wrote:

> Thanks Ric
>
> I wasn't thinking of myself so much, I've got used to the J convention now,
> but more of what would make a good default startup for a newcomer.  I will
> look at the script though, always nice to see how others do it.
>
> As for the capped fork, yes I can live without it, just about, but I
> certainly couldn't when I stared out, especially - as I said - since this
> is the format returned by the 13 : verb.
>
> OK, here's another one:
> I have recently switched over to j701(gtk) from j602.
> On the whole, I like the new colour-coded approach to verb description, but
> sometimes, in complex cases, I really appreciated j602's boxing of the
> structure, which went a long way to make things clear.  (one of J's best
> debugging tools).  Is there a way to emulate this under 702gtk?
>
>
> On 1 December 2012 08:03, Ric Sherlock <tikkanz at gmail.com> wrote:
>
> > Hi Alex,
> > Not sure if you're aware of the trig script available as part of the
> > 'math/misc' addon, but it may contain at least some definitions you'd
> like
> > to use. If you have the addon installed then you can load the definitions
> > using:
> >    require 'trig'
> >
> > If you restrict yourself to writing explicit J then it is perfectly
> > possible to get away without using capped fork.
> >
> > Ric
> >
> >
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