pick(varargin)

function result= pick(varargin)
%
% pick(i, r_0, r_1, ...) returns r_i.  Thus, if i==0, pick() returns the
% second calling argument (r_0); if i==1, pick() returns the third calling
% argument (r_1); and so on. If there is no argument corresponding to i,
% pick() returns an empty matrix.  If pick() is called with fewer than two
% calling arguments, pick() throws an error.
%
% For example, the following returns z= x if flag equals 0 or false and z=
% y if flag equals 1 or true:
%
% z= pick(flag, x, y);
%
% Dr. Phillip M. Feldman, NGST
% 25 May, 2008

if (nargin < 2)
   error('pick() requires a minimum of two calling arguments.');
end

i= varargin{1} + 2;

if (nargin < i)
   result= [];
else
   result= varargin{i};
end