samer@4: % scanrcols - scan array columns from the right
samer@4: %
samer@4: % scanrcols :; 
samer@4: %    ([[M]], [[N]] -> [[M]])   ~'scannning function',
samer@4: %    [[M]]                     ~'initial value',
samer@4: %    [[N,L]]                   ~'data to scan, sequence of length L'
samer@4: % -> [[M,L]].
samer@4: 
samer@4: function Y=scanrcols(f,y,X,varargin)
samer@4: 	Y=zeros(size(y,1),size(X,2));
samer@4: 
samer@4: 	if nargin>3
samer@4: 		opts=prefs('draw',0,varargin{:});
samer@4: 		for i=size(X,2):-1:1
samer@4: 			y1=f(y,X(:,i));
samer@4: 			Y(:,i)=y1;
samer@4: 			if opts.draw, opts.plotfn(i,y,X(:,i),y1);  end
samer@4: 			optpause(opts);
samer@4: 			y=y1;
samer@4: 		end
samer@4: 	else
samer@4: 		for i=size(X,2):-1:1, y=f(y,X(:,i)); Y(:,i)=y; end
samer@4: 	end
samer@4: 		
samer@4: