What is a custom function?

Custom functions are spreadsheet functions which are not built into Fireworkz, but are written by users in Fireworkz custom function language.

There are two parts to a custom function. The first, in your worksheet, is the call to the custom function, which is just like a call to an ordinary function, and specifies how you want to use the custom function.

The second, the custom function definition, specifies what the custom function actually does. This is stored in a special worksheet called a custom function sheet. Custom function sheets are different to ordinary worksheets.

Custom function sheets will usually be supporting documents to single worksheets, and will be loaded automatically when the dependent document is loaded. Remember that it is easiest to keep supporting and dependent documents in the same directory.