Add definition and example of cdf

documents/normal-distribution/normal-distribution.tex

@@ -106,9 +106,11 @@
 \textbf{3.9} & 1.0000 & 1.0000 & 1.0000 & 1.0000 & 1.0000 & 1.0000 & 1.0000 & 1.0000 & 1.0000 & 1.0000\\
         \bottomrule
         \end{tabular}
-        \caption{$\Phi_{0;1}(x + \Delta x)$}
+        \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}(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)
     \end{align*}