< 1 2 >
Arity
The arity is the number of arguments or operands taken by a function or operation.
Explanation
This number is expressed by names as:
| • | Nullary A constant is an operation of arity 0. |
| • | Unary The plus sign and the minus sign are operations of arity 1. |
| • | Binary An addition, a subtraction, a multiplication and a division are operations of arity 2. |
| • | Ternary A ternary operator takes three operands. |
| • | n-ary An n-ary operator takes n operands. |
| • | Varying ary A function can accept a variable number of arguments. |
Example 0
The nullary function f () or the operation time have no argument. The instruction STOP has no operand.
Example 1
The unary function f (x) has the variable x as argument. The operation +1 has only one operand.
Example 2
The binary function f (x, y) has the two variables x and y as argument. The operation x + y has 2 operands.
Example 3
The ternary function f (x, y, z) has the three variables x, y and z as argument.
Example 4
The n-ary function f (x1, x2, . . . , xn) has n variables as argument.
Example 5
The varying ary function with the variable x as argument is written as
The number m is the lower bound of the summation, the number n is its upper bound.