function  w = xpr(xy,t,u)
%XPR    Radial coordinate of t-point of xy-curve rotated through angle u.
%   XPR is a helper function used by TUBE.

%   C. Henry Edwards, University of Georgia. 6-20-93.
%
%   Copyright 1984-2000 The MathWorks, Inc. 
%   $Revision: 5.5 $  $Date: 2000/06/01 03:46:43 $

[xt,yt] = feval(xy,t);

w = xt.*cos(u) - yt.*sin(u);
