Re: [Gretl-devel] Gretl's handling temporary variables
On Tue, 1 Apr 2008, Amir Reza Khosroshahi wrote:
It seems that in gretl, you cannot have temporary variable? that are
generated and then discarded in a command. For example the following
commands are invalid in gretl:
> print $rsq
> smpl $t1+1 $t2
> print 2+2
But commands like these are perfectly logical in other
programming language, and being able to handle variables in this
way makes life much easier!
Gretl's "print" command is special, in that it's oriented towards
printing data series, which can be referred to by ID number in the
data set: thus "print 2" will print the second variable. However,
there are ways of getting the effect you want:
1) Use "eval". I'm afraid this is not documented, I'll have to
add that. But you can do
eval $rsq
eval 2+2
and so on: the result is computed, printed, and discarded.
2) Use "printf" (which is documented):
printf "R-squared = %f\n", $rsq
printf "%g\n", 2+2
As for the behavior with "smpl" -- yes, it would be nice to be
able to use the sort of formulation you give. We'll work on that.
Allin Cottrell