Define Input Variables
An input variable is a system parameter that influences the system performance in the chosen output response. It is an object that is varied by the study based on certain rules.
Input variables can be of different types with respect to their physical and/or numerical nature. Physically they can be dimensions, material properties, locations, and so on. Numerically they can be continuous numbers, discrete, integer, real, strings.
You can associate an input variable to a particular model parameter. Two input variables cannot be associated with the same model parameter. An input variable does not always need to be associated to a model parameter.