function  w = z(xy,t,u)
%ZPR    z-coordinate of t-point of xy-curve rotated through angle u.
%   ZPR is a helper function used by TUBE.
 
%   C. Henry Edwards, University of Georgia. 6-20-93.
%
%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   $Revision: 5.5 $  $Date: 1997/11/21 23:27:48 $

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

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