function marginal = marginal_nodes(engine, nodes, t, add_ev)
% MARGINAL_NODES Compute the marginal on the specified query nodes (loopy_unrolled_dbn)
% marginal = marginal_nodes(engine, nodes, t)
%
% 't' specifies the time slice of the earliest node in 'nodes'.
% 'nodes' must occur in some clique.
%
% Example:
% Consider a DBN with 2 nodes per slice.
% Then t=2, nodes=[1 3] refers to node 1 in slice 2 and node 1 in slice 3,
% i.e., nodes 3 and 5 in the unrolled network,

if nargin < 3, t = 1; end
if nargin < 4, add_ev = 0; end

marginal = marginal_nodes(engine.unrolled_engine, nodes + (t-1)*engine.ss, add_ev);