Other elements in GoldSim represent *functions*. Function elements compute outputs based on defined inputs. That is, they require one or more inputs, carry out a specified calculation on those inputs, and produce one or more outputs. GoldSim provides a wide variety of function elements. The simplest and most general function element is an *Expression*.

Expressions produce a single output by calculating user-specified formulas, such as 2 + 3, A*B, or sqrt(55). Similar to a cell in a spreadsheet, when defining an Expression, you can use a wide variety of mathematical operators and functions. You can even use conditional operators (e.g., >,<, =) and “if, then” logic to define Expressions.

Other function elements have predefined functionality. For example, a *Selector* provides an easy way to create nested* ***if,then** logic.