Mauch MIREX 2010

function pot = convert_to_pot(CPD, pot_type, domain, evidence)

% CONVERT_TO_POT Convert a gmux CPD to a Gaussian potential

% pot = convert_to_pot(CPD, pot_type, domain, evidence)

switch pot_type

 case {'d', 'u', 'cg', 'scg'},

  error(['can''t convert gmux to potential of type ' pot_type])

 case {'c','g'},

  % We create a large weight matrix with zeros in all blocks corresponding

  % to the non-chosen parents, since they are effectively disconnected.

  % The chosen parent is determined by the value, m,  of the discrete parent.

  % Thus the potential is as large as the whole family.

  ps = domain(1:end-1);

  dps = ps(CPD.dps); % CPD.dps is an index, not a node number (because of param tying)

  cps = ps(CPD.cps);

  m = evidence{dps};

  if isempty(m)

    error('gmux node must have observed discrete parent')

  end

  bs = CPD.sizes(CPD.cps);

  b = block(m, bs);

  sum_cpsz = sum(CPD.sizes(CPD.cps));

  selfsz = CPD.sizes(end);

  W = zeros(selfsz, sum_cpsz);

  W(:,b) = CPD.weights(:,:,m);

  ns = zeros(1, max(domain));

  ns(domain) = CPD.sizes;

  self = domain(end);

  cdom = [cps(:)' self];

  pot = linear_gaussian_to_cpot(CPD.mean(:,m), CPD.cov(:,:,m), W, domain, ns, cdom, evidence);

 otherwise,

  error(['unrecognized pot_type' pot_type])

end