|Definition:|| relation f such that for any entity a there is exactly one entity b to which a is related by f|
Note 1 to entry: If a is related to b by the function f, then:
- f is said to be defined for a,
- a is an argument of the function f,
- b is a value of the function f and is usually denoted by f(a).
The argument may be an elementary entity, such as a number, or an ordered set of elementary entities, and the same for the value.
Note 2 to entry: If A is the set of all arguments of the function f and B is a set containing all the values, then:
- f is said to be a mapping of A into B,
- A is the domain of the function,
- B is the range or codomain of the function.
Note 3 to entry: The term "function" may be qualified according to the nature of the value, e.g. real function, complex function, vector function, or to the character of the relation, e.g. algebraic function, trigonometric function, hyperbolic function.
Note 4 to entry: The term "operation" is used for elementary arithmetic functions such as addition, subtraction, multiplication, division, and also for logical functions.
Note 5 to entry: The term "operation" has other meanings in IEV 151-11-28 and IEV 151-11-30.