Remove unnecessary comma.
diff --git a/Doc/lib/libcmath.tex b/Doc/lib/libcmath.tex
index 378615b..3a11870 100644
--- a/Doc/lib/libcmath.tex
+++ b/Doc/lib/libcmath.tex
@@ -83,7 +83,7 @@
Note that the selection of functions is similar, but not identical, to
that in module \refmodule{math}\refbimodindex{math}. The reason for having
-two modules is, that some users aren't interested in complex numbers,
+two modules is that some users aren't interested in complex numbers,
and perhaps don't even know what they are. They would rather have
\code{math.sqrt(-1)} raise an exception than return a complex number.
Also note that the functions defined in \module{cmath} always return a