samer@0: function y=expdata(A,B,N,M)
samer@0: % expdata - exponential data sequence
samer@0: %
samer@0: % expdata :: 
samer@0: %    real  ~'initial value',
samer@0: %    real  ~'final value',
samer@0: %    natural ~'number of steps (sequence length is steps+1),
samer@0: %    M:natural ~'buffer size'
samer@0: % -> seq [[1,M]].
samer@0: 
samer@0: if nargin<4, M=1; end
samer@0: 
samer@0: lA=log(A);
samer@0: k=(log(B)-lA)/N;
samer@0: y=unfold(@ls1,0:M-1);
samer@0: %y=windowdata(linspace(A,B,N),M,M);
samer@0: 
samer@0: function [X,I]=ls1(I), 
samer@0: 	surp=I(end)-N;
samer@0: 	if surp>=0,
samer@0: 		X=exp(lA+k*I(1:end-surp)); 
samer@0: 		if surp<M, X(end)=B; end
samer@0: 	else
samer@0: 		X=exp(lA+k*I); 
samer@0: 	end
samer@0: 	I=I+M; 
samer@0: end
samer@0: 
samer@0: end
samer@0: