function  nt= plot4v(t,x,i)
%
% plot4(t,x,i):
%
% Function to plot 4 subplots with the plot layout being 
% 2 plots per row and 2 plots per line, ending with the I-th component.
% First plot represents the sum of components from I-3 to I-th,
% 2-nd plot represents the sum of components from I-2 to I-th,
% 3-ird plot represents the sum of components from I-1 to I-th. 
% Input-
%	t	- vector that represents the data coordinates
%	x	- 2-D array of component data
%	i	- start plot at component i
% Output-
%	nt	- the handler of the figure
%
% J.Marshak (NASA GSFC)		24 Apr.2004 Modified
%				(changed the alghorithm to make it work).

close;

tn=length(t);
for j=i-3:i
   y=sum(x(:,j:i),2);
   y1=min([x(:,j); y]);
   y2=max([x(:,j); y]);
   subplot(2,2,j+4-i),plot(t,x(:,j), ':', t, sum(x(:,j:i),2)');
   axis([t(1) t(tn) y1 y2]);	
   s0='Sum cx from';
   s1=' to';
   s2=[s0 num2str(j) s1 num2str(i)];
   title(s2);
end
nt=1;