The lookup table block computes an approximation to some function y=f(t) given data vector y. By default t is the current time point of the simulation, but can also be sent as an argument when calling the lookup table.
A lookup table can be cyclic, meaning that it repeats itself when asked for data outside of the time frame given. It can also be set to either interpolate/extrapolate values or to return values as a step function.
Lookup tables are used to represent time series inputs in MERLIN-Expo, and are listed in the time series screen.