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Web Intelligence functions
Overview
This chapter looks at the functions available in Web Intelligence. You often use functions
when creating Web Intelligence custom calculations. For more information on custom
calculations, see ”Creating custom calculations” on page 307.
This chapter covers the following topics:
•
what is a function?
• using functions
• function examples and descriptions
What is a function?
In mathematics, a function is a rule relating different values or sets of values. Functions
describe the relationships between variables and allow you to determine the value of one
variable given the value of another variable or variables. A function prototype (see below)
is a description of the relationship between input value(s) and output values and allows
you to derive a value (the output value) given zero or more existing values (the input value
or values). You input values to a function through its parameters and the function returns a
value related to the values of the parameters.
For example, the
Left() function describes the relationship between two input values (a
character string and an integer) and a character string output value. It outputs the first
[integer] characters of this character string as another character string. If the input string is
‘Hello’ and the input integer is 2, the output string is therefore ‘He’.
Note: Not all functions require input parameters.
Function prototypes
To use a function you need to know its name, how many input values it requires and the
data types of these input values. You also need to know the type of data that the function
outputs.
For example, the Sum function takes a numerical object as input (for example a measure
showing sales revenue) and outputs numeric data (the sum of all the values of the measure
object).