Functions for fitting linear and non-linear mixed-effects models using
stochastic differential equations (SDEs). The package allows for any multivariate
non-linear time-variant model to be specified, and it also handles multidimensional
input, covariates, missing observations, and specification of dosage regimen.
The provided pipeline relies on the coupling of the FOCE algorithm and Kalman filtering
as outlined by Klim et al (2009,