)</i>
<a name="IDX2169"></a>
</dt>
<dd><p>Calculates the ratio Benefit/Cost.  Benefit is the Net Present Value (NPV)
of the inputs, and Cost is the Net Present Value (NPV) of the outputs.
Notice that if there is not an input or output value in a specific period,
the input/output would be a zero for that period.
<var>rate</var> is the interest rate, <var>input</var> is a list of input values,
and <var>output</var> is a list of output values.
</p>
<p>Example:
</p>
<pre class="example">(%i1) load(finance)$
(%i