Abstract: User-defined function capabilities in a spreadsheet application allow users to create new named functions that are defined using the spreadsheet formula paradigm. A user may define spreadsheet functions from formulae entered in a worksheet or function sheet of a spreadsheet application. The formula interface is well known to spreadsheet users; therefore, expanding the formula feature to provide encapsulated functions that can be imported, exported, customized, and compiled supplies new power and flexibility to users who do not wish to learn a programming language. Furthermore, the user-defined functions in spreadsheets represent vectors and matrices as “first class” values, similar to Boolean values, numbers, and strings.