[Gretl-users] Loop problems

[Allin Cottrell]

On Thu, 19 Jul 2007, Johannes Fichtinger wrote:

> first of all, thank you a lot for that great piece of software! 

Glad you like it!

> Now, I have some questions regarding the use of loops in gretl. 
> I have some many datasets in one gretl file like x1 y1 x2 y2 x3 
> y3 ... x80 y80, where x-y stands for a pair of variables such 
> that e.g. x1 is the independent, explanatory variable of y1, x2 
> explains y2 and so on.
> 
> 1. First, I would like to run in a script a simple regression like:
> 
> loop i=1..80
> ols $i+1 const $i
> endloop

"$i+1" is not going to work here.  If you need to refer to the 
variables by number -- and they go, "x1" = 1, "y1" = 2, and so on 
-- you can do this:

# run 8 regressions, yi on xi
loop for (i = 1; i <= 8; i += 2)
  sprintf yvar "%d", i+1
  ols @yvar 0 $i
end loop

The gretl 1.6.5 release doesn't support the "sprintf" command in 
loops, but the current snapshot does:

http://ricardo.ecn.wfu.edu/pub/gretl/gretl_install.exe

> the command gnuplot is not available in loop mode. This brings 
> me to my last question: Why are some commands not available in 
> loop mode? This behaviour was somehow surprising for me.

Some commands raise special complications in a loop context.  
However, gnuplot is probably not one of these, so I'll probably 
enable it, after some testing.

Allin Cottrell