The Extras pane contains some options which have an impact on model fitting.
Parameters |
This configuration is only related to the compartment models and determines which initial values are used for the iterative fitting:
|
Model |
Behavior of the parameters when switching between models. |
Fit blood |
If this box it is checked on, all parameters of the Input curves which have the fit box checked are also included into the set of fitted parameters. This feature has two uses:
Note: When using Fit All, the blood parameters will not be fitted, even if Fit blood is enabled. |
Single fit |
Default mode of performing one single fit. |
Random |
This configuration is only related to models which require iterative fitting:
Note: The purpose of randomized fitting is to avoid local minima, but there is still a chance that the returned solution may contain unphysiological parameter combinations. |
Grid fits |
This configuration is only related to models which require iterative fitting:
|
Data |
Enables a sequence of fits with a successively shorter data segment to study the parameter sensitivity to acquisition duration. |
Fitting |
Selection of the numerical optimization method applied for iterative fitting:
The iterative optimizations terminate, when no substantial improvement can be found any more, or when the Max iterations restriction is hit. Note: Several models (linear and multi-linear regression) are not fitted iteratively because they have closed form solutions. In these cases the Fitting method settings are not relevant. |
Max. |
Maximal number of iterations which are allowed in the iterative Marquardt and Powell fitting. |
Note the set of radio buttons in the taskbar to the right for enabling/disabling some of the options quickly.
The Init and Conv boxes correspond to Parameters initialization and Model conversion, respectively. The Sng, Rnd and Grd radio buttons switch between Single, Randomized or Grid fitting.