function plottime(X,n)
%  plottime --> Plot discrete time signals.
%
%  <Synopsis>
%    plottime(X)
%    plottime(X,n)
%
%  <Description>
%    Plot matrix of discrete time signals versus sample index n.
%
%  <See Also>
%    plotstem --> Plot sample values of discrete time signals.

%  <Revision>
%    Peter S.K. Hansen, IMM, Technical University of Denmark
%
%    Last revised: February 7, 2000
%-----------------------------------------------------------------------

% Check the required input arguments.
if (nargin < 1)
  error('Not enough input arguments.')
elseif (nargin==1)
  n = 1:max(size(X));
end

set(gcf,'DefaultAxesFontName','Times', ...
        'DefaultAxesLineStyleOrder','-|--|-.|:');

plot(n,X);

x_min = min(min(X));
if (x_min>0)
  x_min = 0.9*x_min;
else
  x_min = 1.1*x_min;
end  

x_max = max(max(X));
if (x_max>0)
  x_max = 1.1*x_max;
else
  x_max = 0.9*x_max;
end  

if (n(1)==0)
  axis([n(1) n(length(n))+1 x_min x_max]);
else
  axis([n(1)-1 n(length(n))+1 x_min x_max]);
end

xlabel('Sample Number, {\it n}');
ylabel('Amplitude');

%-----------------------------------------------------------------------
% End of function plottime
%-----------------------------------------------------------------------