Hello, thank you very much for your idea for an implementation for my problem! It works the way I want it to! Therefore I will need some time to wholly understand it :) BFN, with kind regards, Raindrop -- View this message in context: http://www.nabble.com/Problem-with-defrule-tf1902175.html#a5207604 Sent from the Maxima forum at Nabble.com.