basis-plus-class: Basis Functions for Functional Data
In yixuan/fdaplus: Enhancement of the 'fda' package for functional data analysis

The "basis+" class is the base class for all basis function objects, including bspline+ and fourier+.

range: A length-two numeric vector to define the interval on which basis functions can be evaluated.
nbasis: The total number of basis functions, including the ones that need to be dropped.
dropind: Indices of basis functions that need to be dropped.
ncoef: The actual number of basis functions to represent functional data, satisfying the condition ncoef == nbasis - length(dropind).