scg_unrolled_dbn_inf_engine.m

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function engine = scg_unrolled_dbn_inf_engine(bnet, T, varargin)
% SCG_UNROLLED_DBN_INF_ENGINE Unroll the DBN for T time-slices and apply stab_cond_gauss to the resulting static net
% engine = scg_unrolled_dbn_inf_engine(bnet, T, ...)
%
% The following optional arguments can be specified in the form of name/value pairs:
% [default value in brackets]
%
% constrained - 1 means we constrain ourselves to eliminate slice t before t+1 [1]
%

% set default params
N = length(bnet.intra);
constrained = 1;

if nargin >= 3
  args = varargin;
  nargs = length(args);
  for i=1:2:nargs
    switch args{i},
     case 'constrained',  constrained = args{i+1};
     otherwise,  
      error(['invalid argument name ' args{i}]);       
    end
  end
end

bnet2 = dbn_to_bnet(bnet, T);
ss = length(bnet.intra);
engine.ss = ss;

% If constrained_order = 1 we constrain ourselves to eliminate slice t before t+1.
% This prevents cliques containing nodes from far-apart time-slices.
if constrained
  stages = num2cell(unroll_set(1:ss, ss, T), 1);
else
  stages = { 1:length(bnet2.dag) };
end
scg_engine = stab_cond_gauss_inf_engine(bnet2, 'stages', stages);

engine.unrolled_engine = scg_engine;
% we don't inherit from jtree_inf_engine, because that would only store bnet2,
% and we would lose access to the DBN-specific fields like intra/inter

engine.nslices = T;
engine = class(engine, 'scg_unrolled_dbn_inf_engine', inf_engine(bnet));