 overestimated
outside the support of the inducing inputs.
In a multivariate example where densely sampled inducing inputs are infeasible,
one can simply use a random subset of the training points. 
</p>

<pre>
  nu = fix(n/2); iu = randperm(n); iu = iu(1:nu); u = x(iu,:);
</pre>

<center><img src="f5.gif" alt="f5.gif"></center><br>

<h4>Exercises for the reader</h4>

<dl>
<dt><strong>Inference Methods</strong>
<dd>Try using Expectation Propagation instead of exact inference in
  the above, by exchanging <t