% ISVECTOR ISVECTOR Test For a Vector
% 
% Usage
% 
% This function tests to see if the argument is a vector.  The 
% syntax for isvector is
% 
%    x = isvector(y)
% 
% and it returns a logical 1 if the argument is size N x 1 or
% 1 x N and a logical 0 otherwise.
function y = isvector(x)
  s = size(x);
  y = isempty(x) || (prod(s) == (s(1)*s(2))) && ((s(1) == 1) || (s(2) == 1));