Added matrix examples

scratch.page

@@ -42,3 +42,39 @@ This follows from **Bayes' Theorem** which says
 $$
 P(A|B) = \frac{P(B | A)\, P(A)}{P(B)}
 $$
+
+# Matrix Stuff
+This is a column vector:
+$$\vec v = \left(\begin{matrix}
+1\\
+3\\
+7
+\end{matrix}\right)$$
+
+The *vector sum* of $\vec u$ and $\vec v$ is:
+
+$$\vec u + \vec v =
+\left(\begin{matrix}
+u_1\\
+\vdots\\
+u_n
+\end{matrix}\right) + \left(\begin{matrix}
+v_1\\
+\vdots\\
+v_n
+\end{matrix}\right) = \left(\begin{matrix}
+u_1 + v_1\\
+\vdots\\
+u_n + v_n
+\end{matrix}\right)
+$$
+
+The *scalar multiplication* of the real number $r$ and the vector $\vec v$ is:
+
+$$
+r \cdot \vec v = r \cdot \left(\begin{matrix}
+v_1\\ \vdots \\ v_n
+\end{matrix}\right) = \left(\begin{matrix}
+rv_1 \\ \vdots \\ rv_n
+\end{matrix}\right)
+$$