### Control variables

DEPRECATED in version 5. These user variables used to affect fit behaviour.

       FIT_LIMIT - use `set fit limit <epsilon>`
       FIT_MAXITER - use `set fit maxiter <number_of_cycles>`
       FIT_START_LAMBDA - use `set fit start-lambda <value>`
       FIT_LAMBDA_FACTOR - use `set fit lambda-factor <value>`
       FIT_SKIP - use the datafile `every` modifier
       FIT_INDEX - See `fit multi-branch`