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-rw-r--r--content/know/concept/central-limit-theorem/index.pdc14
1 files changed, 7 insertions, 7 deletions
diff --git a/content/know/concept/central-limit-theorem/index.pdc b/content/know/concept/central-limit-theorem/index.pdc
index a957736..518c224 100644
--- a/content/know/concept/central-limit-theorem/index.pdc
+++ b/content/know/concept/central-limit-theorem/index.pdc
@@ -53,7 +53,7 @@ $$\begin{aligned}
\phi(k) = \int_{-\infty}^\infty p(x) \exp(i k x) \dd{x}
\end{aligned}$$
-Note that $\phi(k)$ can be interpreted as the average of $\exp(i k x)$.
+Note that $\phi(k)$ can be interpreted as the average of $\exp\!(i k x)$.
We take its Taylor expansion in two separate ways,
where an overline denotes the mean:
@@ -62,7 +62,7 @@ $$\begin{aligned}
= \sum_{n = 0}^\infty \frac{k^n}{n!} \: \phi^{(n)}(0)
\qquad
\phi(k)
- = \overline{\exp(i k x)} = \sum_{n = 0}^\infty \frac{(ik)^n}{n!} \overline{x^n}
+ = \overline{\exp\!(i k x)} = \sum_{n = 0}^\infty \frac{(ik)^n}{n!} \overline{x^n}
\end{aligned}$$
By comparing the coefficients of these two power series,
@@ -88,12 +88,12 @@ using our earlier relation:
$$\begin{aligned}
C^{(1)}
&= - i \dv{k} \Big(\ln\!\big(\phi(k)\big)\Big) \big|_{k = 0}
- = - i \frac{\phi'(0)}{\exp(0)}
+ = - i \frac{\phi'(0)}{\exp\!(0)}
= \overline{x}
\\
C^{(2)}
&= - \dv[2]{k} \Big(\ln\!\big(\phi(k)\big)\Big) \big|_{k = 0}
- = \frac{\big(\phi'(0)\big)^2}{\exp(0)^2} - \frac{\phi''(0)}{\exp(0)}
+ = \frac{\big(\phi'(0)\big)^2}{\exp\!(0)^2} - \frac{\phi''(0)}{\exp\!(0)}
= - \overline{x}^2 + \overline{x^2} = \sigma^2
\end{aligned}$$
@@ -153,7 +153,7 @@ with $\sqrt{N}$ appearing in the arguments of $\phi_n$:
$$\begin{aligned}
\phi_z(k)
&= \idotsint
- \Big( \prod_{n = 1}^N p(x_n) \Big) \: \delta\Big( z - \frac{1}{\sqrt{N}} \sum_{n = 1}^N x_n \Big) \exp(i k z)
+ \Big( \prod_{n = 1}^N p(x_n) \Big) \: \delta\Big( z - \frac{1}{\sqrt{N}} \sum_{n = 1}^N x_n \Big) \exp\!(i k z)
\dd{x_1} \cdots \dd{x_N}
\\
&= \idotsint
@@ -184,7 +184,7 @@ $$\begin{aligned}
= i k \overline{z} - \frac{k^2}{2} \sigma_z^2
\\
\phi_z(k)
- &\approx \exp(i k \overline{z}) \exp\!(- k^2 \sigma_z^2 / 2)
+ &\approx \exp\!(i k \overline{z}) \exp\!(- k^2 \sigma_z^2 / 2)
\end{aligned}$$
We take its inverse Fourier transform to get the density $p(z)$,
@@ -194,7 +194,7 @@ which is even already normalized:
$$\begin{aligned}
p(z)
= \hat{\mathcal{F}}^{-1} \{\phi_z(k)\}
- &= \frac{1}{2 \pi} \int_{-\infty}^\infty \exp\!\big(\!-\! i k (z - \overline{z})\big) \exp(- k^2 \sigma_z^2 / 2) \dd{k}
+ &= \frac{1}{2 \pi} \int_{-\infty}^\infty \exp\!\big(\!-\! i k (z - \overline{z})\big) \exp\!(- k^2 \sigma_z^2 / 2) \dd{k}
\\
&= \frac{1}{\sqrt{2 \pi \sigma_z^2}} \exp\!\Big(\!-\! \frac{(z - \overline{z})^2}{2 \sigma_z^2} \Big)
\end{aligned}$$