Update after a fit

Syntax: | `FIT\UPDATE yout`

The `FIT\UPDATE` command evaluates the previously fitted expression, that is, the expression in the last `FIT` command, for the current parameter values, and stores this result in the vector `yout`.

This is exactly equivalent to entering: `yout=`previously_fitted_expression and is provided only to obviate the necessity of re-entering a complicated expression.

Note: The vector name `yout` usually differs from the name of the vector being fitted to avoid destroying the original data.

Number of iterations
Normal distribution