Re: [Gretl-devel] some function suggestions/questions
On Tue, 4 Aug 2009, Sven Schreiber wrote:
Allin Cottrell schrieb:
>
> * 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.
Also fine with me, especially because it's an optional argument.
However, one thing may be important to repeat (one last time, I
promise): From what I remember from the discussion, this will be
the first function in gretl with a boolean switch, right?
Yes, I think that's right, and I see your point; I'm not very
happy about it. It would definitely be more consistent either to
offer rreverse and creverse, or to require mreverse(a')' for
turning a matrix upside down.
> 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).
> * 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!
>
Ok, fair enough. But then I have a related question: You said there will
be T/2 calculated values of the spectrum. But which ones exactly, what's
the formula to determine the spacing? Linear, geometrical etc. etc. Is
it somewhere in the docs?
http://gretl.cvs.sourceforge.net/viewvc/*checkout*/gretl/gretl/lib/src/de...
and look for "real_periodogram".
Allin.