orderselect.m

剑桥大学用于线性和双线性动力学系统辨识的工具箱

function n = orderselect(order,SIGMA)
%ORDERSELECT   Select the model order.
%
%   Used in the functions BILINID and SUBID3B.   
%
% CUED System Identification Toolbox.
% Cambridge University Engineering Department.
% Copyright (C) 1998-2002. All Rights Reserved.

% Version 1.00, Date: 01/06/2002
% Created by H. Chen and E.C. Kerrigan.
 
if isempty(order);   %  no order is given as input
  n = min(rank(SIGMA),10);
  disp(['Model order n = ',int2str(n),'.'])
else
  kk = length(order);
  if kk > 1
	order = sort(order(:));
	eigvalue = zeros(1,kk);
	for kkk=1:kk
	  try
		eigvalue(kkk) = SIGMA(order(kkk),order(kkk));
	  catch
		error('The block size is incompatible with this choice of order.')
	  end
	end         
	eigvalue = log(eigvalue);
	%plot(order,eigvalue,'k*')
	bar(order,eigvalue)
	axis([min(order)-1 max(order)+1 min(eigvalue)*.9 max(eigvalue)*1.1])
	title('Model Order Selection')
	xlabel('Model order')
	ylabel('Log singular value')	
	n = input('Please select model order: ');
	if isempty(n)
	  n = min(rank(SIGMA),10);
	  disp(['Model order n = ',int2str(n),'.'])
	else
	  if ~(n > 0 & fix(n) == n)
		error('Model order must be a positive integer.')
	  end
	end
	close(gcf)
  else
	n = order;
  end 
end

% *** last line of orderselect.m ***