wolffd@0: function y = sample_node(CPD, pev)
wolffd@0: % SAMPLE_NODE Draw a random sample from P(Y|pa(y), theta)  (root)
wolffd@0: % Y = SAMPLE_NODE(CPD, PEV)
wolffd@0: %
wolffd@0: % pev{i} is the evidence on the i'th parent.
wolffd@0: % Since a root has no parents, we ignore pev,
wolffd@0: % and return the value the root was clamped to when it was created.
wolffd@0: 
wolffd@0: y = CPD.val;