nd the natural logarithm of y. <span class="math display">\[
\text{lmultiply}(x,y) = \begin{cases} 0 &amp; \text{if } x = y = 0 \\ x
\log y &amp; \text{if } x, y \neq 0 \\ \text{NaN} &amp; \text{otherwise}
\end{cases} \]</span></p>
<!-- R; log1p; (T x); -->
<p></p>
<p><code>R</code> <strong><code>log1p</code></strong><code>(T x)</code><br>
natural logarithm of 1 plus x</p>
<!-- R; log1m; (T x); -->
<p></p>
<p><code>R</code> <strong><code>log1m</code></strong><code>(T x)</code><br>
natural logarithm of 1 min