For analysis: functions or expressions?
Formal calculation with Maple

A Maple function is a program for calculating a value from arguments. There are two stages to this process, which must be clearly distinguished:

• definition of the function, in which formal parameters representing the arguments are used to indicate how the value taken by the function is to be calculated. This definition often takes the form of an assignment instruction, assigning a name to the function;

• function calls, where we actually calculate the values taken by the function for specific argument values, called effective parameters.

For the moment, we're only considering elementary functions, whose values can be calculated...