Locating max/min of 3d surface

How could I go about locating the global min/max of a user input function. The GUI plots a function based on user input:

% Get the function  
  g=get(handles.funcxy,'String');
% Get the x limits
  limit=[str2num(char(get(handles.xmin,'String'))),...      str2num(char(get(handles.xmax,'String')))];
% Convert to inline for plotting  
  func=inline(char(g));
% Set axes to draw on
  axes(handles.plot);
% Plot the surface defined by a function f(x,y)=func
  ezsurf(func,limit);

I have figured out in order to find the z maximum I can do

sh=ezsurf(func,limit);
setappdata(0, 'function', char(g));

zd=get(sh,'zdata');
zmax=max(max(zd));

But how can I get the corresponding x,y points

Answer 1

[Jared]

I found the answer myself so I figured I might as well post the solution for anyone else.

sh=ezsurf(func,limit);
zd=get(sh,'zdata');
xd=get(sh,'xdata');
yd=get(sh,'ydata');
% Construct 3xa matrix of data points (X,Y,Zmax)
while a<=size(i,1)
    A(1,a)=xd(i(a));
    A(2,a)=yd(i(a));
    A(3,a)=zmax;
    a=a+1;
end

[Walter Roberson]

You do not calculate zmax within that code ?