concentrations from a linear compartment model by close-form solutions
lin_cmt(obs_time, dose_time, dose, Tinf, params, oral, infusion, ncmt,
parameterization)times at which an observation is desired
times at which doses are given
a vector of doses
a vector of infusion duration
model-appropriate parameters per parameterization
logical, whether oral absorption is true
logical, whether infusion is true
number of compartments
type of parameterization, 1=clearance/volumn, 2=micro-constants
calculated concentrations