ement corresponding to a different planning
unit. It should have the same number of planning units as those
in the argument to <code>x</code>. Additionally, any planning units missing
cost (<code>NA</code>) values should also have missing (<code>NA</code>) values in the
argument to <code>solution</code>.</p></dd>


<dt><code>x</code> has <code>matrix</code> planning units</dt>
<dd><p>The argument to <code>solution</code> must be a
<code>matrix</code> vector with each row corresponding to a different plannin