[Gretl-devel] some function suggestions/questions

[Riccardo (Jack) Lucchetti]

On Fri, 31 Jul 2009, Allin Cottrell wrote:

> OK, here's my considered round-up.  I'm thinking that a 1.8.3
> release would be good soon, given the number of fixes we've racked
> up to date, so that informs my perspective.
>
> * sort-plus-dsort versus a single sort function with an optional
> boolean argument to reverse the sort:
>
> Ho-hum.  On the one hand everyone knows that sorting can go two
> ways, so the boolean option is reasonable.  On the other hand, we
> have dsort as a separate function historically and does saving one
> place in the function namespace merit backward incompatibility?

Of course not. Let's keep dsort.

> * mreverse-with-boolean versus rreverse plus creverse:
>
> Again, ho-hum.  IMO the specialized nature of this function (we
> managed without it for quite some time) means that we're OK with
> the boolean switch.
>
> Next, I take it that we don't really want to replace all the
> existing m*/r* and *m/*r matrix-function pairs with single
> functions having an extra row/column boolean argument.  (If we do,
> it won't be in gretl 1.8.3!)

I agree.

> Alright, that leaves the pergm() function, which has been added in
> CVS since gretl 1.8.2 (so that I can't appeal to history). I think
> I hear Jack wanting less options/arguments (scrap the optional
> Bartlett window size), and Sven wanting more arguments (add a
> parameter to govern the number of rows in the output matrix).
>
> Here I'm tempted to propose the typical wretched British
> compromise of leaving things as they are (Bartlett option present,
> no other options available).  Rationale:
>
> * The Bartlett option may be worth keeping since it's not totally
> trivial for the user to reconstruct (as Sven has said).
>
> * But it is fairly trivial to sample the rows of the returned
> matrix, if you happen to have a ginormous time series and want a
> reduced spectrum matrix.  The alternative involves some tedious
> error-checking on whatever the user has thrown at us for the
> number of rows to be returned.  Coder to user: if you're smart
> enough to be in the frequency domain, you ought to be smart
> enough to figure it out yourself!

Fine by me!



Riccardo (Jack) Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche

r.lucchetti at univpm.it
http://www.econ.univpm.it/lucchetti