comparison toolboxes/FullBNT-1.0.7/bnt/potentials/@scgpot/recursive_combine_pots.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function pot = recursive_combine_pots(pot1, pot2)
+% RECURSIVE_COMBINE_POTS recursive combine two potentials
+% pot = recursive_combine_pots(pot1, pot2)
+
+pot1 = reduce_pot(pot1);
+pot2 = reduce_pot(pot2);
+% Recursion is stopped, if recusive-combination is defined by direct combination, 
+% i.e. if the domain of one potential is disjoint from the head of the other.
+if (isempty(myintersect(pot1.domain,pot2.cheaddom))|...
+    isempty(myintersect(pot1.cheaddom,pot2.domain)))    
+    pot = direct_combine_pots(pot1,pot2);
+else 
+    % Test wether one of the set-differences is not empty 
+    % as defined in Lauritzen99 "Stable Local Computation with Conditional Gaussian Distributions"
+    % on page 9
+    D12 = mysetdiff(pot1.cheaddom, pot2.domain);
+    D21 = mysetdiff(pot2.cheaddom, pot1.domain);
+    if (isempty(D12) & isempty(D21))
+       assert(0,'Recursive combination is not defined');
+    end
+
+    if ~isempty(D12)
+        % Calculate the complementary potential for the set 
+        % D1\D12 as defined in Lauritzen 99, page 9
+    keep = mysetdiff(pot1.domain,D12);
+        [margpot, comppot] = complement_pot(pot1,keep);
+        margpot = reduce_pot(margpot);
+        comppot = reduce_pot(comppot);
+        pot = direct_combine_pots( recursive_combine_pots(margpot, pot2), comppot);
+    elseif ~isempty(D21)
+        keep = mysetdiff(pot2.domain,D21);
+        [margpot, comppot] = complement_pot(pot2,D21);
+        margpot = reduce_pot(margpot);
+        comppot = reduce_pot(comppot);
+        pot = direct_combine_pots( recursive_combine_pots(pot1, margpot), comppot);
+    end
+end
+
+
+