# Fit the Linear and Nonlinear Terms in the Model

The purpose of this step is to fit all of the data, for example, the frequencies, amplitudes and preloads, to all of the parameters in the model.

- The output from Fit the Linear Terms in the Model is used as the starting point for yet another optimization run.
- All terms in the model, linear and nonlinear, are included in the calculations.
- The entire set of data, all frequencies, amplitudes and preloads, are fitted.
- The optimizer returns when it has either met its goal or when it cannot further reduce the cost function.
- The following plot shows the effect of a global fit: