# Defining Variables

**Parent topic**Workflow for Performing Design Studies

**Previous topic**Setting the Properties of a Design Study

**Next topic**Defining Constraints

## Defining Continuous Variables

Define continuous variables to perform optimization. You cannot perform an Evaluation Design Study using continuous variables. A continuous variable is one which has any value (whole, rational, and irrational) between the minimum and the maximum values. For example, 2.131567 is a valid value between a minimum value of 2 and a maximum value of 5.

## Defining Discrete Variables Using Variable View

Set discrete variables to evaluate scenarios or perform optimization. If you perform optimization with discrete variables only, the program selects the optimal solution from one of the defined scenarios. A discrete variable is defined by a specific value. For example, 3,4,4.2,5 represents a set of discrete values.