[Gretl-users] trouble with matrix functions

[Riccardo (Jack) Lucchetti]

On Wed, 30 Jan 2008, nadaud at centre-cired.fr wrote:

> Hi listers, greetings from Paris !
>
> I am in big trouble with matrix functions under GRETL 1.7.0 under XP.
>
> The problem is the following:
>
> I run system estimation (SUR) on microdata (10 305 households).

[...]

> This is puzzeling because, in another script, with *exactly the same data and 
> the same code*, the computations run ok .
>
> Note that i checked the sizes of the other matrices :
>
> I just redo the computation on the main script and it runs ok !
>
> any advice ? I am a bit lost !

Let me recap: you're adding two column vectors; the second one is obtained 
by dividing a scalar by all the elemnts of a column vector. 
\footnote{You could have used the syntax a./b, but this is immaterial.}

There has been some work recently in the area of casting a 1x1 matrix to a 
scalar, and a few bugs were fixed. Try using 1.7.1, or perhaps the 
snapshot version. Alternatively, try what happens after substituting the 
line

matrix erlog = vecun + (coeffaids[4,1]).*(1/what[,1])

with

scalar tmp = coeffaids[4,1]
matrix erlog = vecun + tmp.*(1/what[,1])

or, better still,

scalar tmp = coeffaids[4,1]
matrix erlog = vecun + tmp./what[,1]

What worries me more than this is that, unless I'm mistaken, a practically 
identical scripts triggers a different behaviour. Maybe you're using two 
different PCs with different versions of gretl?


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

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