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1 function [reduced_pot,successful] = reduce_pot(pot,tailnodes)
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2 % Executes the reduce operation defined in
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3 % Stable Local Computation with Conditional Gaussian Distributions
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4 % Steffen L. Lauritzen
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5 % Frank Jensen
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6 % September 1999
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7 % The potential pot is reduced if B contains any zero columns
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8 % The test are restricted to the positions in tailnodes.
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9 % Any columns successfully deleted are entered in the array successful
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10 if nargin < 2
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11 tailnodes = pot.ctaildom;
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12 end
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13
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14 successful = [];
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15 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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16 % Keep track of remaining tailnodes %
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17 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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18 rem_tailnodes = pot.ctaildom;
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19 for i = tailnodes
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20 pos = find(i==rem_tailnodes);
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21 successful_red = [pos];
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22 red_scgcpot = cell(1,pot.dsize);
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23 j = 1;
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24 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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25 % Test whether all components of pot.scgpotc can be reduced %
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26 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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27 while ((j <= pot.dsize) & ~isempty(successful_red))
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28 [cpot,successful_red] = reduce_pot(pot.scgpotc{j},pos);
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29 red_scgcpot{j} = cpot;
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30 j = j + 1;
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31 end
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32
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33 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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34 % If i is a reducible tailnode, then reduce the potential %
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35 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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36 if ~isempty(successful_red)
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37 successful = [successful i];
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38 pot.scgpotc = red_scgcpot;
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39 rem_tailnodes = mysetdiff(rem_tailnodes,i);
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40 end;
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41 end
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42
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43 pot.ctaildom = rem_tailnodes;
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44 positions = find_equiv_posns(rem_tailnodes,pot.ctaildom);
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45 pot.ctailsizes = pot.ctailsizes(positions);
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46 pot.ctailsize = sum(pot.ctailsizes);
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47 pot.domain = mysetdiff(pot.domain,successful);
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48 reduced_pot = pot;
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49
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50
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51
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52
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53
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