parse_formula_nonlin: Simple Formula Interface for Grouped Nonlinear Functions
Description
This simple formula interface handles formulae of the form
dependent ~ FUN(independent, parms) | group1 + group2 + ....
Usage
parse_formula_nonlin(formula)
Value
a list with the elements FUN, valuevar, timevar,
and groups
Arguments
formula
a model formula specifying dependent and
independent variables, nonlinear model and grouping variables in the form:
dependent ~ FUN(independent, parms) | group1 + group2 + ....
FUN can be a name of an existing growth model (e.g. grow_logistic)
or a valid user-defined function (see growthmodel).
Details
This function is used by all_growthmodels and normally not
called for the user.