diff sequences/rndseq.m @ 3:3f77126f7b5f

First major revision of sequence library, now using classdef form, STILL A BIT BROKEN!

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sequences/rndseq.m	Wed Jan 09 22:22:21 2013 +0000
@@ -0,0 +1,54 @@
+% rndseq - Sequence of values sampled from a random variable model
+%
+% rndseq ::
+% 	  model xdom:[[1,XD]]   ~ random variable model, data size is xdom,
+% 	  sdom:[[1,SD]],        ~ size of sample,
+% -> seq([[xdom sdom]]) ~ size of rndseq is product of xdom and sdom
+%
+% rndseq ::
+% 	  model xdom:[[1,XD]]   ~ random variable model, data size is xdom,
+% 	  sdom:[[1,SD]],        ~ size of sample,
+% 	  rndstate              ~ initial state of generators
+% -> rndseq([[xdom sdom]]) ~ size of rndseq is product of xdom and sdom
+%
+% If an initial rndstate is supplied, rndseq is purely functional
+% and referentially transparent. Otherwise, the initial construction
+% uses the current state of the random generators. After this, the
+% entire sequence is fully determined.
+% 
+% EXAMPLE
+%
+%  rndseq(gaussian,[2,200]) :: seq [[2,200]]
+% 	rndseq(dirichlet(3,0.5),6) :: seq [[3,6]]
+function d=rndseq(model,sdom,k)
+	if nargin<2, sdom=1; end
+	if isa(model,'struct')
+		if model.nparams>0,
+			error('Model has unbound parameters');
+		end
+		gen=sampler(model.sample,sdom);
+	elseif iscell(model)
+		gen=sampler(model{1},sdom);
+	end
+
+	if nargin>2, 
+		if ~iscell(k), s={k,k}; else s=k; end 
+	else
+		s=getrndstate;
+	end
+	d=unfoldseq(gen,s);
+end
+
+% this creates a rand-state-managed version of g applied to args,
+% ie,
+% sampler :: 
+%    ((A1,A2,....) -> random B) ~'an action which generates a value'
+% -> (rndstata -> B, rndstate)  ~'a deterministic random state transformer'.
+function f=sampler(g,varargin)
+	f=@ufn;
+	function [x,s]=ufn(s)
+		setrndstate(s); x=g(varargin{:});
+		s=getrndstate;
+	end
+end
+