[Gretl-users] problem concerning dummies

Hello! I need to create some dummy variables in order to capture all the possible combinations of a certain set of variables. For instance, let's assume I have three variables a, b, c. I need one dummy equal to 1 when all three variables are positive, zero otherwise. I need one dummy equal to 1 when all three variables are negative, zero otherwise. I need one dummy equal to 1 when a and b are positive and c negative, zero otherwise. I need one dummy equal to 1 when a and c are positive and b negative, zero otherwise. Etc etc etc... I would do this in Excel since my database is taken from a csv, but the actual number of variables is much higher then 3, so it takes a lot of time to do it manually. I don't have any idea if it is possible to create these dummies automatically with some piece of code in GretL, but if it is I would really really appreciate your help in writing this code. Thank you very much in advance. Cheers, Paolo