function [x, uels] = readgdx(gdxFileName,gdxSymName)
% syntax: [x, uels] = readgdx ('gdxFileName', 'gdxSymName')
%
% For example,
% [x, uels] = readgdx('tang.gdx','foo'); 
%
% Read the coordinate/index information from the GDX symbol
% 'gdxSymName' into Matlab.  The output is a matrix that contains the
% data of the set or parameter 'gdxSymName'.
% 'gdxSymName' can read a set or parameter of any valid dimension.
%
% Assume gdxSymName has dimension d and cardinality C
% if gdxSymName is a set,
%   the output x will have size(x) = [C,d]
%   where each row of x contains the indices for an element in gdxSymName
% if gdxSymName is a parameter,
%   the output x will have size(x) = [C,d+1]
%   where each row of x contains the indices for an element in gdxSymName
%   with the (d+1)'st column being the value for that element
% The optional output uels returns the UEL list of the gdx file
