function q=pol90(a,x,u,cn)

% The function POL90 plots contours of a 2-D data in polar coordinates
% with 0 degrees located at the 12 o'clock position and 
% degrees increasing counter-clockwise.
% To add labels to the contours do: 
%	 hold on; eclabel(q,'fontsize',6); .
% Non MATLAB Library routine called is: POLARH.
%
% Calling sequence-
% q=pol90(a,x,u,cn)
%
% Input-
%	a	- the radius
%	x	- the x-y axis column vector
%	u	- the matrix (issued from ro2xy.cpp)
%	cn	- number of contours
% Output-
%	q	- the handle of the figure
%
% See also-     
% POLARH, RO2XY.cpp.


close
r=a*ones(200,1);
d=linspace(0,2*pi,200)';
polarh(d,r);
%polarh(d,r);
hold on
ss=max(max(u));
u=rot90(u)-2*ss;   %rot90 make theta=0 at the top
%u=u-2*ss;   %rot90 make theta=0 at the top
q=contour(x,x,flipud(u),cn);
hold off