# Types of Response Variables

Nine types of response variables are available by default to choose from.

Nine types of response variables are available by default to choose from.

**At Time**

Captures the value of a given solver expression at a given time.**At Reference Signal Value**

Captures the value of a given expression when a given reference signal expression achieves a certain value (reference signal value).**Root Mean Square Deviation**

Calculates the RMS difference value between a give expression and a desired curve.**Slope**

Captures the slope of the curve derived from two expressions at a particular instance of time.**Slope Deviation**

Captures the square deviation of the slope of the curve derived from two expressions at an instance of time, from a target value.**Generic**

Calculates a response value using any generic solver expression or a subroutine.**Max Val**

Captures the maximum value of a given expression.**Min Val**

Captures the minimum value of a given expression.**Response Expression**

Derives a response using a mathematical expression involving other responses and design variables.