On Mon, 14 Feb 2005, Renju Jacob wrote: The nls command is now usable in loops, in gretl CVS -- there will be a new Windows snapshot shortly. Also, there is an internal variable, $nvars, accessible via the genr command, that holds the number of variables in the current dataset (including the constant). I don't fully understand the context you have in mind, but I suspect that these changes may not be sufficient to do what you want. In the context of an nls command, variables must be referenced by name, not number (since numeric constants are also valid in that context). So you have to know the names of the relevant variables to construct a suitable gretl loop. I suppose that's OK if you know that the dependent variable is called "y" and the independent variables are always called "x1",...,"xn". I'm inclined to repeat my previous advice: this seems to me a case where an external scripting language might well be used to construct a set of driver scripts for gretl. Gretl has very minimal string handling, whereas scripting languages are at home with that sort of thing. Allin Cottrell