cision that depends on how close they are. This is easy to see in
practice. Consider</p>
<pre><code>  1.23456789012345
- 1.23456789012344
= 0.00000000000001</code></pre>
<p>We start with fifteen decimal places of accuracy in the arguments and
are left with a single decimal place of accuracy in the result.</p>
<p>Catastrophic cancellation arises in statistical computations whenever
we calculate variance for a distribution with small standard
deviations relative to its location. When calculating summary
stati