A function returns a value. For example, log( and sin( are functions. In general, the first letter of each function is lowercase. Most functions take at least one argument, as indicated by an open parenthesis following the name. For example, sin( requires one argument, sin(value).
Note: To see the arguments of a function or command in the calculator, find the item in a menu or y N and press +. For most menu items, a Catalog Help screen will display and the syntax of the arguments will be displayed.