[Gretl-devel] some function suggestions/questions

Allin Cottrell cottrell at wfu.edu
Mon Jul 20 17:55:49 EDT 2009


On Mon, 20 Jul 2009, Sven Schreiber wrote:

> in light of the recent discussion concerning mreverse() --for example we
> don't want too many different functions for doing similar things-- I
> would like to raise the following issues:
>
> 1) sort() and dsort(); IMHO it would be good to unify them into one
> function with an optional argument to specify descending sorting, like so:
> sort(a) or sort(a,0) : sorts ascending
> sort(a,1): sorts descending

Maybe so.  My only misgiving is that I prefer not to use magic
numbers (or magic booleans) as function arguments -- though we
already do this to some extent.

> 2) strcmp(): would it be possible to handle this with a comparison
> operator like mystr1 == mystr2 and scrap the function?

Ah, perhaps I had forgotten that we already implement s1 == s1 for
strings, when I added strcmp.  So maybe strcmp is redundant.

> 3) if not, at least unify strcmp() and strncmp(), again using an
> optional argument:
> strcmp(a,b,5) would work just like strncmp(a,b,5)
> Actually, this looks very straightforward, or am I missing something?

Well, for "str" functions that have the same names as C functions
I think it's desirable that they have the same syntax as the C
versions.

> I'm aware these are backward-incompatible changes, so of course this
> needs to be carefully discussed and thought through. These are just some
> things I stumbled upon recently, I guess there are similar issues that
> could be found if done systematically.

I agree that's worth looking for useful pruning opportunities.

> And one last thing: I may have asked this before, but having a function
> similar to the command 'pergm' would be useful I think.

OK, it's added, though not documented yet: pergm(x) returns a
2-column matrix with omega in column 1 and the spectral density
in column 2.

Allin.


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