The second argument is the number to
   approximate. <a href="Num.html#VALapprox_num_fix"><code class="code"><span class="constructor">Num</span>.approx_num_fix</code></a> uses decimal notation; the first
   argument is the number of digits after the decimal point.
   <code class="code">approx_num_exp</code> uses scientific (exponential) notation; the
   first argument is the number of digits in the mantissa.<br>
</div>

<pre><span id="VALnum_of_string"><span class="keyword">val</span> num_of_string</span> 