A complex metric in Optimize is one that is based on other metrics (simple and/or complex). A complex metric is built up in three components: Numerator (N), Denominator (D), and Right Hand Side (RHS). The RHS component itself can be either another metric or a constant value, and can be connected to N/D with one of the four arithmetic signs.

Effectively therefore, a complex metric can take forms such as:

- N/D = straight ratio of two metrics
- N (plus/minus/times/divided by) RHS metric = sum (or difference, product, division) of two metrics
- N (plus/minus/times/divided by) RHS constant = constant applied to a metric
- N/D (plus/minus/times/divided by) RHS metric = sum (or difference, product, division) of a ratio and another metric
- N/D (plus/minus/times/divided by) RHS constant = constant applied to a ratio

Note that not all of these forms lead to valid objective or constraint functions, although such metrics can still be valid for reporting.

Defining an optimization metric in LityxIQ is explained here: https://support.lityxiq.com/773516-Define-Optimization-Metrics.