Mauch MIREX 2010

function CPT = CPD_to_CPT(CPD)

% Compute the big CPT for an HHMM Q node (including F parents)

% by combining internal transprob and startprob

% function CPT = CPD_to_CPT(CPD)

Qsz = CPD.Qsz;

if ~isempty(CPD.Fbelow_ndx)

  if ~isempty(CPD.Fself_ndx) % general case

    error('not implemented')

  else % no F from self, hence no startprob (top level)

    nps = length(CPD.dom_sz)-1; % num parents

    CPT = 0*myones(CPD.dom_sz);

    % when Fself=1, the CPT(i,j) = delta(i,j) for all k

    for k=1:prod(CPD.Qpsizes)

      Qps_vals = ind2subv(CPD.Qpsizes, k);

      ndx = mk_multi_index(nps+1, [CPD.Fbelow_ndx CPD.Qps_ndx], [1 Qps_vals]);

      CPT(ndx{:}) = eye(Qsz); % CPT(:,2,k,:) or CPT(:,k,2,:) etc

    end

    ndx = mk_multi_index(nps+1, CPD.Fbelow_ndx, 2);

    CPT(ndx{:}) = CPD.transprob; % we assume transprob is in topo order

  end

else % no F signal from below

  if ~isempty(CPD.Fself_ndx) % bottom level

    nps = length(CPD.dom_sz)-1; % num parents

    CPT = 0*myones(CPD.dom_sz);

    ndx = mk_multi_index(nps+1, CPD.Fself_ndx, 1);

    CPT(ndx{:}) = CPD.transprob;

    ndx = mk_multi_index(nps+1, CPD.Fself_ndx, 2);

    CPT(ndx{:}) = CPD.startprob;

  else % no F from self

    error('An hhmmQ node without any F parents is just a tabular_CPD')

  end

end