You don't need the local assignment in the definition of Wave. If you delete "a<--" it works just the same. All you are doing is assigning the results of the calculation to a local variable "a" (the left shaft is a local assignment, and "a" is only defined within the expression - you can't access it somewhere else in the worksheet), and then assigning the contents of "a" to "Wave". Since you don't use "a" for anything else, it's not needed.
Richard
