diff --git a/doc/math.lyx b/doc/math.lyx
index 55d83ab10..05eb355ad 100644
--- a/doc/math.lyx
+++ b/doc/math.lyx
@@ -4728,7 +4728,10 @@ between
  in its first argument,
 \begin_inset Formula 
 \[
-\frac{\partial\left(T_{1}^{^{-1}}T_{2}\right)}{\partial\xi_{1}}=-\Ad{T_{2}^{^{-1}}T_{1}}
+\frac{\partial\left(T_{1}^{^{-1}}T_{2}\right)}{\partial\xi_{1}}=-\Ad{T_{2}^{^{-1}}T_{1}}=\left[\begin{array}{cc}
+-R_{2}^{T}R_{1} & 0\\
+R_{2}^{T}\left[t_{2}-t_{1}\right]_{\times}R_{1} & -R_{2}^{T}R_{1}
+\end{array}\right]
 \]
 
 \end_inset
@@ -5177,7 +5180,7 @@ Aligning 3D Scans
 \end_layout
 
 \begin_layout Standard
-Below is the explanaition underlying Pose3.align, i.e.
+Below is the explanation underlying Pose3.align, i.e.
  aligning two point clouds using SVD.
  Inspired but modified from CVOnline...
 \end_layout
diff --git a/doc/math.pdf b/doc/math.pdf
index 1dfc781c8..eb429095c 100644
Binary files a/doc/math.pdf and b/doc/math.pdf differ