smoothAPC - Smoothing of Two-Dimensional Demographic Data, Optionally Taking into Account Period and Cohort Effects

The implemented method uses for smoothing bivariate thin plate splines, bivariate lasso-type regularization, and allows for both period and cohort effects. Thus the mortality rates are modelled as the sum of four components: a smooth bivariate function of age and time, smooth one-dimensional cohort effects, smooth one-dimensional period effects and random errors.