comparison toolboxes/FullBNT-1.0.7/bnt/inference/static/@gibbs_sampling_inf_engine/private/compute_strides.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function strides = compute_strides(bnet)
+% COMPUTE_STRIDES For each CPT and each variable in that CPT,
+% returns the stride of that variable.  So in future, we can
+% quickly extract a slice of the CPT.
+%
+% The return value is a 2d array, where strides(i,j) contains the
+% stride of the jth variable in the ith CPT.  Cell arrays would
+% have saved space but they are slower.
+% 
+
+num_cpts = size(bnet.CPD, 2);
+max_cpt_dim = 1 + max(sum(bnet.dag));
+strides = zeros(num_cpts, max_cpt_dim);
+
+for i = 1:num_cpts
+  c = CPT(bnet, i);
+  siz = size(CPT(bnet, i));
+  
+  % Deal with the special case of a 1-d array separately
+  if siz(2) == 1
+    dim = 1;
+  else
+    dim = size(siz, 2);
+  end
+
+  strides(i, 1:dim ) = [1 cumprod(siz(1:dim-1))];
+end