Custom functions

This section describes how to use and write custom functions within your Fireworkz spreadsheets. It explains what a custom function is, and when it might be useful to create one, and goes on to show you how to create a custom function and to describe the tools provided by Fireworkz for this purpose.

What is a custom function?

Custom function libraries

Using custom functions

Writing custom functions

The FUNCTION function

Custom function control statements

Editing custom functions

Declaring the result

Recalculation and custom function sheets

Before you start to use and write custom functions, you will need to understand all the components of Fireworkz spreadsheets, including functions, ranges, arrays and external references. If you are unsure about any of these, read the appropriate section(s) of the User Guide.