Add missing normalization factor

documents/normal-distribution/normal-distribution.tex

@@ -109,7 +109,7 @@
         \caption{Approximations of $\Phi_{0;1}(x + \Delta x)$}
     \end{table}
     \begin{align*}
-        \Phi_{0;1}(x) &= \int_{-\infty}^{x} e^{- t^2 / 2} \mathrm{d} t &
+        \Phi_{0;1}(x) &= \frac{1}{\sqrt{2 \pi}} \int_{-\infty}^{x} e^{- t^2 / 2} \mathrm{d} t &
         \Phi_{0;1}(1.65) &\approx 0.9505\\
         \Phi_{\mu; \sigma^2}(x) &= \Phi_{0;1} \left (\frac{x-\mu}{\sigma} \right ) &
         \Phi_{0;1}(-x) &= 1 - \Phi_{0;1}(x)