Hi. I recently turned over to maple 13, after using TI InterActive! for 2 years. But i am having som problems working with vector functions in maple. Here is a link to the PDF file with the exercise in TI: https://docs.google.com/fileview?id=0Bx5y79IuSOVJNTAxNmJmODAtOGY3OC00NWRhLWI0ZTgtMzBmOWJhMzYzMDMw&hl=en It's when i reach "Opgave 2d" that i get into trouble.. when i differentiate the r(t) function it just gives me an error.. "non-algebraic expressions cannot be differentiated" And im just wondering wether there are other functions in maple to differentiate vector functions?