samer@3: % rndseq - Sequence of values sampled from a random variable model
samer@3: %
samer@3: % rndseq ::
samer@3: % 	  model xdom:[[1,XD]]   ~ random variable model, data size is xdom,
samer@3: % 	  sdom:[[1,SD]],        ~ size of sample,
samer@3: % -> seq([[xdom sdom]]) ~ size of rndseq is product of xdom and sdom
samer@3: %
samer@3: % rndseq ::
samer@3: % 	  model xdom:[[1,XD]]   ~ random variable model, data size is xdom,
samer@3: % 	  sdom:[[1,SD]],        ~ size of sample,
samer@3: % 	  rndstate              ~ initial state of generators
samer@3: % -> rndseq([[xdom sdom]]) ~ size of rndseq is product of xdom and sdom
samer@3: %
samer@3: % If an initial rndstate is supplied, rndseq is purely functional
samer@3: % and referentially transparent. Otherwise, the initial construction
samer@3: % uses the current state of the random generators. After this, the
samer@3: % entire sequence is fully determined.
samer@3: % 
samer@3: % EXAMPLE
samer@3: %
samer@3: %  rndseq(gaussian,[2,200]) :: seq [[2,200]]
samer@3: % 	rndseq(dirichlet(3,0.5),6) :: seq [[3,6]]
samer@3: function d=rndseq(model,sdom,k)
samer@3: 	if nargin<2, sdom=1; end
samer@3: 	if isa(model,'struct')
samer@3: 		if model.nparams>0,
samer@3: 			error('Model has unbound parameters');
samer@3: 		end
samer@3: 		gen=sampler(model.sample,sdom);
samer@3: 	elseif iscell(model)
samer@3: 		gen=sampler(model{1},sdom);
samer@3: 	end
samer@3: 
samer@3: 	if nargin>2, 
samer@3: 		if ~iscell(k), s={k,k}; else s=k; end 
samer@3: 	else
samer@3: 		s=getrndstate;
samer@3: 	end
samer@3: 	d=unfoldseq(gen,s);
samer@3: end
samer@3: 
samer@3: % this creates a rand-state-managed version of g applied to args,
samer@3: % ie,
samer@3: % sampler :: 
samer@3: %    ((A1,A2,....) -> random B) ~'an action which generates a value'
samer@3: % -> (rndstata -> B, rndstate)  ~'a deterministic random state transformer'.
samer@3: function f=sampler(g,varargin)
samer@3: 	f=@ufn;
samer@3: 	function [x,s]=ufn(s)
samer@3: 		setrndstate(s); x=g(varargin{:});
samer@3: 		s=getrndstate;
samer@3: 	end
samer@3: end
samer@3: