Daniel@0: function [reduced_pot,successful] = reduce_pot(pot,tailnodes)
Daniel@0: % Executes the reduce operation defined in
Daniel@0: % Stable Local Computation with Conditional Gaussian Distributions
Daniel@0: % Steffen L. Lauritzen
Daniel@0: % Frank Jensen
Daniel@0: % September 1999
Daniel@0: % The potential pot is reduced if B contains any zero columns
Daniel@0: % The test are restricted to the positions in tailnodes.
Daniel@0: % Any columns successfully deleted are entered in the array successful
Daniel@0: if nargin < 2
Daniel@0:     tailnodes = pot.ctaildom;
Daniel@0: end
Daniel@0: 
Daniel@0: successful = [];
Daniel@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Daniel@0: % Keep track of remaining tailnodes %
Daniel@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Daniel@0: rem_tailnodes = pot.ctaildom;
Daniel@0: for i = tailnodes
Daniel@0:     pos = find(i==rem_tailnodes);
Daniel@0:     successful_red = [pos];
Daniel@0:     red_scgcpot = cell(1,pot.dsize);
Daniel@0:     j = 1;
Daniel@0:     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Daniel@0:     % Test whether all components of pot.scgpotc can be reduced %
Daniel@0:     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Daniel@0:     while ((j <= pot.dsize) & ~isempty(successful_red))
Daniel@0:         [cpot,successful_red] = reduce_pot(pot.scgpotc{j},pos);
Daniel@0:         red_scgcpot{j} = cpot;
Daniel@0:         j = j + 1;
Daniel@0:     end
Daniel@0: 
Daniel@0:     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Daniel@0:     % If i is a reducible tailnode, then reduce the potential %
Daniel@0:     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Daniel@0:     if ~isempty(successful_red)
Daniel@0:         successful = [successful i];
Daniel@0:         pot.scgpotc = red_scgcpot;
Daniel@0:         rem_tailnodes = mysetdiff(rem_tailnodes,i);
Daniel@0:     end;
Daniel@0: end
Daniel@0: 
Daniel@0: pot.ctaildom = rem_tailnodes;
Daniel@0: positions = find_equiv_posns(rem_tailnodes,pot.ctaildom);
Daniel@0: pot.ctailsizes = pot.ctailsizes(positions);
Daniel@0: pot.ctailsize = sum(pot.ctailsizes);
Daniel@0: pot.domain = mysetdiff(pot.domain,successful);
Daniel@0: reduced_pot = pot;
Daniel@0: 
Daniel@0: 
Daniel@0: 
Daniel@0: 
Daniel@0: