function [f, logscale] = fwd(engine, fpast, ev, t)% Forwards pass.f.obslik = mk_hmm_obs_lik_vec(engine, ev);transmat = engine.transprob;f.past_alpha = fpast.alpha;if engine.maximize  Q = length(fpast.alpha);  A = repmat(fpast.alpha, [1 Q]);  m = max(transmat .* A, [], 1);  [f.alpha, scale] = normalise(m(:) .* f.obslik);else  [f.alpha, scale] = normalise((transmat' * fpast.alpha) .* f.obslik);endlogscale = log(scale);%f.xi = normalise((fpast.alpha * obslik') .* transmat); % t-1,tf.t = t;