'1 Function call' calculates the value of the likelihood function for the current parameter estimates of the active model.

Typically, the likelihood function is either the negative-ln likelihood of the data, or twice that value; but it might also be the sum-of-squares which is related to the negative ln-likelihood by a scalar constant.

The choice of '1 Function call' lists the current value of the likelihood function as well as the values and descriptions of all parameters, whether or not they are fixed or free.

No distinction is made on this form between fixed and free parameters, though fused parameters are identified.

This choice also gives an estimate of the time required to calculate one function call of the model.

This can be informative of the time that might be required to obtain a model fit, if you also have a sense of the number of function calls that might be required.

More function calls are required for models with more, more uncertain, and (at least some) highly correlated parameters.