As a first step of a Sensitivity analysis, a model is defined or loaded (using the Model editor). A model is generally defined with a number of input parameters and model outputs where the model outputs are allowed to be time dependent. Different kinds of models are supported by Eikos:

• An expression: a model made up of coupled equations. Each equation is built up of scalar parameters, other equations and mathematical functions (e.g. sin(x), x^y). An expression can also be time dependent by including the reserved variable time.
• An ecolego model.
• An external executable model. Windows .exe and .bat executables are supported. How to access an external model from eikos.

The more general case when output samples can somehow be generated given values of input parameters is also supported (see the section Importing and exporting data).