function plotperdisc(x)
% FUNCTION:     plotperdisc                    Part of DPWT Toolbox
%
% SYNOPSIS:     plotperdisc(X)
%
% DESCRIPTION:  Plot a sequence over the discrete circle. The sequence
%               is assumed to be normalized so that its max and min
%               values lie between -1 and 1. The sequence is plotted 
%               around a circle. Three circles indicate the -1 value
%               0 value and 1 value.
% 
% NOTE:         X is assumed to be prescaled to be between -1 and 1
%
% EXAMPLE:      plotperdisc(sin(0:.1:2*pi))

% AUTHOR:       Neil Getz
% DATE:		3-30-94
if(nargin ~= 1),
  help plotperdisc,
  return;
end;

GAP = 1/7; %size of space between zero circle and 1 circle

xx = GAP*row(x);

lenxx = length(xx);
theta = 0: 2*pi/lenxx : 2*pi;
st = sin(theta);
ct = cos(theta);
A = zeros(2*lenxx,2*lenxx);

xy = zeros(2*lenxx,2);
for i = 1:length(xx),
  xy(2*i - 1,:) = [st(i), ct(i)]*2*GAP; % from point
  xy(2*i,:) = [st(i), ct(i)]*(2*GAP+xx(i)); % to point
  A(2*i - 1, 2*i) = 1;
  A(2*i, 2*i - 1) = 1;
end
gplot(A,xy);
axis('square');
axis('off');

hold on;
if (length(theta)<300)
   longtheta = 0:2*pi/300:2*pi;
   longst = sin(longtheta);
   longct = cos(longtheta);
   plot(2*GAP*[longst, longst(1)], 2*GAP*[longct, longct(1)],'r-', ...
      3*GAP*[longst, longst(1)], 3*GAP*[longct, longct(1)],'r-', ...
      1*GAP*[longst, longst(1)], 1*GAP*[longct, longct(1)],'r-');
else,
   plot(2*GAP*[st, st(1)], 2*GAP*[ct, ct(1)],'r-', ...
   3*GAP*[st, st(1)], 3*GAP*[ct, ct(1)],'r-', ...
   1*GAP*[st, st(1)], 1*GAP*[ct, ct(1)],'r-');
end
hold off;