Patch #826074: cmath.log optional base argument, fixes #823209
(Contributed by Andrew Gaul.)
diff --git a/Doc/lib/libcmath.tex b/Doc/lib/libcmath.tex
index 77496bf..465c8fd 100644
--- a/Doc/lib/libcmath.tex
+++ b/Doc/lib/libcmath.tex
@@ -73,10 +73,12 @@
Return the exponential value \code{e**\var{x}}.
\end{funcdesc}
-\begin{funcdesc}{log}{x}
-Return the natural logarithm of \var{x}.
+\begin{funcdesc}{log}{x\optional{, base}}
+Returns the logarithm of \var{x} to the given \var{base}.
+If the \var{base} is not specified, returns the natural logarithm of \var{x}.
There is one branch cut, from 0 along the negative real axis to
-\infinity, continuous from above.
+\versionchanged[\var{base} argument added]{2.4}
\end{funcdesc}
\begin{funcdesc}{log10}{x}