function engine = smoother_engine(tbn_engine)% SMOOTHER_ENGINE Create an engine which does offline (fixed-interval) smoothing in O(T) space/time% function engine = smoother_engine(tbn_engine)%% tbn_engine is any 2TBN inference engine which supports the following methods:% fwd, fwd1, back, backT, back, marginal_nodes and marginal_family.engine.tbn_engine = tbn_engine;engine.b = []; % space to store smoothed messagesengine = class(engine, 'smoother_engine');%engine = class(engine, 'smoother_engine', inf_engine(bnet_from_engine(tbn_engine)));