p><code>romberg(<var>expr</var>, <var>x</var>, <var>a</var>, <var>b</var>)</code>
returns an estimate of the integral <code>integrate(<var>expr</var>, <var>x</var>, <var>a</var>, <var>b</var>)</code>.
<var>expr</var> must be an expression which evaluates to a floating point value
when <var>x</var> is bound to a floating point value.
</p>
<p><code>romberg(<var>F</var>, <var>a</var>, <var>b</var>)</code>
returns an estimate of the integral <code>integrate(<var>F</var>(x), x, <var>a</var>, <var>b</var>)</code>