| Spread Silverlight Documentation > Formula Reference > Formula Overview > Functions in a Formula |
Functions are code segments that perform calculations by using specific values, called arguments, in a particular order that can be used in formulas. For example, the SUM function adds values or ranges of cells and the PMT function calculates the loan payments based on an interest rate, the length of the loan, and the principal amount of the loan. Functions may be either built-in functions that come with Spread or user‑defined functions that you create.
Arguments can be numbers, text, logical values, arrays, cell ranges, cell references, or error values. The value you use for an argument must be valid for the given function. Arguments can also be constants, formulas, or other functions. Using a function as an argument for another function is known as nesting a function. Some arguments are optional; this reference displays "[Optional]" before the description of the argument for those arguments that are not required.
The structure of a function begins with the function name, followed by an opening parenthesis, the arguments for the function separated by commas, and a closing parenthesis. If you are entering the function into a cell directly, type an equal sign (=) before the function name.
This control has the following types of functions: