diff --git a/doc/pub/week42/html/._week42-bs062.html b/doc/pub/week42/html/._week42-bs062.html
index 984df9d52..f6a8c1296 100644
--- a/doc/pub/week42/html/._week42-bs062.html
+++ b/doc/pub/week42/html/._week42-bs062.html
@@ -404,7 +404,7 @@ which are non-zero, we can rewrite the above convolution expressions
 as a matrix-vector multiplication
 
 $$
-\boldsymbol{\delta}=\begin{bmatriax}\alpha_0 & 0 & 0 & 0 \\
+\boldsymbol{\delta}=\begin{bmatrix}\alpha_0 & 0 & 0 & 0 \\
                             \alpha_1 & \alpha_0 & 0 & 0 \\
 			    \alpha_2 & \alpha_1 & \alpha_0 & 0 \\
 			    0 & \alpha_2 & \alpha_1 & \alpha_0 \\
diff --git a/doc/pub/week42/html/week42-reveal.html b/doc/pub/week42/html/week42-reveal.html
index c9cd01597..6872511cb 100644
--- a/doc/pub/week42/html/week42-reveal.html
+++ b/doc/pub/week42/html/week42-reveal.html
@@ -3306,7 +3306,7 @@ as a matrix-vector multiplication
 
 <p>&nbsp;<br>
 $$
-\boldsymbol{\delta}=\begin{bmatriax}\alpha_0 & 0 & 0 & 0 \\
+\boldsymbol{\delta}=\begin{bmatrix}\alpha_0 & 0 & 0 & 0 \\
                             \alpha_1 & \alpha_0 & 0 & 0 \\
 			    \alpha_2 & \alpha_1 & \alpha_0 & 0 \\
 			    0 & \alpha_2 & \alpha_1 & \alpha_0 \\
diff --git a/doc/pub/week42/html/week42-solarized.html b/doc/pub/week42/html/week42-solarized.html
index 1591bb175..2dd74bff4 100644
--- a/doc/pub/week42/html/week42-solarized.html
+++ b/doc/pub/week42/html/week42-solarized.html
@@ -3318,7 +3318,7 @@ which are non-zero, we can rewrite the above convolution expressions
 as a matrix-vector multiplication
 
 $$
-\boldsymbol{\delta}=\begin{bmatriax}\alpha_0 & 0 & 0 & 0 \\
+\boldsymbol{\delta}=\begin{bmatrix}\alpha_0 & 0 & 0 & 0 \\
                             \alpha_1 & \alpha_0 & 0 & 0 \\
 			    \alpha_2 & \alpha_1 & \alpha_0 & 0 \\
 			    0 & \alpha_2 & \alpha_1 & \alpha_0 \\
diff --git a/doc/pub/week42/html/week42.html b/doc/pub/week42/html/week42.html
index 009050326..cb0d00497 100644
--- a/doc/pub/week42/html/week42.html
+++ b/doc/pub/week42/html/week42.html
@@ -3323,7 +3323,7 @@ which are non-zero, we can rewrite the above convolution expressions
 as a matrix-vector multiplication
 
 $$
-\boldsymbol{\delta}=\begin{bmatriax}\alpha_0 & 0 & 0 & 0 \\
+\boldsymbol{\delta}=\begin{bmatrix}\alpha_0 & 0 & 0 & 0 \\
                             \alpha_1 & \alpha_0 & 0 & 0 \\
 			    \alpha_2 & \alpha_1 & \alpha_0 & 0 \\
 			    0 & \alpha_2 & \alpha_1 & \alpha_0 \\
diff --git a/doc/pub/week42/ipynb/ipynb-week42-src.tar.gz b/doc/pub/week42/ipynb/ipynb-week42-src.tar.gz
index 1dfa21863..0d7e50f97 100644
Binary files a/doc/pub/week42/ipynb/ipynb-week42-src.tar.gz and b/doc/pub/week42/ipynb/ipynb-week42-src.tar.gz differ
diff --git a/doc/pub/week42/ipynb/week42.ipynb b/doc/pub/week42/ipynb/week42.ipynb
index a75354186..510408be9 100644
--- a/doc/pub/week42/ipynb/week42.ipynb
+++ b/doc/pub/week42/ipynb/week42.ipynb
@@ -3475,7 +3475,7 @@
    "metadata": {},
    "source": [
     "$$\n",
-    "\\boldsymbol{\\delta}=\\begin{bmatriax}\\alpha_0 & 0 & 0 & 0 \\\\\n",
+    "\\boldsymbol{\\delta}=\\begin{bmatrix}\\alpha_0 & 0 & 0 & 0 \\\\\n",
     "                            \\alpha_1 & \\alpha_0 & 0 & 0 \\\\\n",
     "\t\t\t    \\alpha_2 & \\alpha_1 & \\alpha_0 & 0 \\\\\n",
     "\t\t\t    0 & \\alpha_2 & \\alpha_1 & \\alpha_0 \\\\\n",
diff --git a/doc/src/week42/week42.do.txt b/doc/src/week42/week42.do.txt
index 99cd9b644..c2d55cf94 100644
--- a/doc/src/week42/week42.do.txt
+++ b/doc/src/week42/week42.do.txt
@@ -2704,7 +2704,7 @@ as a matrix-vector multiplication
 
 !bt
 \[
-\bm{\delta}=\begin{bmatriax}\alpha_0 & 0 & 0 & 0 \\
+\bm{\delta}=\begin{bmatrix}\alpha_0 & 0 & 0 & 0 \\
                             \alpha_1 & \alpha_0 & 0 & 0 \\
 			    \alpha_2 & \alpha_1 & \alpha_0 & 0 \\
 			    0 & \alpha_2 & \alpha_1 & \alpha_0 \\