FIT_LIMIT
The maximum number of iterations may be limited by declaring a value for
FIT_MAXITER
If you need even more control about the algorithm, and know the
Marquardt-Levenberg algorithm well, there are some more variables to
influence it. The startup value of lambda is normally calculated
automatically from the ML-matrix, but if you want to, you may provide
your own one with
FIT_START_LAMBDA
FIT_LAMBDA_FACTOR
Other variables with the FIT_ prefix may be added to fit, so it is safer not to use that prefix for user-defined variables.
The variables FIT_SKIP and FIT_INDEX were used by earlier releases of gnuplot with a 'fit' patch called gnufit and are no longer available. The datafile every modifier provides the functionality of FIT_SKIP. FIT_INDEX was used for multi-branch fitting, but multi-branch fitting of one independent variable is now done as a pseudo-3D fit in which the second independent variable and using are used to specify the branch. See fit multi-branch (p. ).