In side a text chunk, you can use mathematical notation if you surround it by dollar signs $ for “inline mathematics” and $$ for “displayed equations”. Do not leave a space between the $ and your mathematical notation.
Example: $\sum_{n=1}^{10} n^2$ is rendered as \(\sum_{n=1}^{10} n^2\).
Example: $$\sum_{n=1}^{10} n^2$$ is rendered as \[\sum_{n=1}^{10} n^2\].
The mathematical typesetting is based on LaTeX, so if you need to search for the way to make a particular symbol, include latex in your search. But note: Not all LaTeX macros are available without using additional packages, and those packages likely will only work if you are creating a PDF. On the plus side, if you are working in PDF, you can use additional packages that give much better control and/or easier syntax.
In LaTeX,
\){ and }) are used to surround items that are to be considered as one object from LaTeX’s perspective.$$\sum_x=1^10 x^2$$ produces \[\sum_x=1^10 x^2\]Here are some common mathematical things you might use in statistics. (Note: Some of these look better in PDF than in HTML.)
| \(x = y\) |
$x = y $
|
| \(x < y\) |
$x < y $
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| \(x > y\) |
$x > y $
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| \(x \le y\) |
$x \le y $
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| \(x \ge y\) |
$x \ge y $
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| \(x^{n}\) |
$x^{n}$
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| \(x_{n}\) |
$x_{n}$
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| \(\overline{x}\) |
$\overline{x}$
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| \(\hat{x}\) |
$\hat{x}$
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| \(\tilde{x}\) |
$\tilde{x}$
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| \(\frac{a}{b}\) |
$\frac{a}{b}$
|
| \(\frac{\partial f}{\partial x}\) |
$\frac{\partial f}{\partial x}$
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| \(\displaystyle \frac{\partial f}{\partial x}\) |
$\displaystyle \frac{\partial f}{\partial x}$
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| \(\binom{n}{k}\) |
$\binom{n}{k}$
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| \(x_{1} + x_{2} + \cdots + x_{n}\) |
$x_{1} + x_{2} + \cdots + x_{n}$
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| \(x_{1}, x_{2}, \dots, x_{n}\) |
$x_{1}, x_{2}, \dots, x_{n}$
|
| \(\mathbf{x} = \langle x_{1}, x_{2}, \dots, x_{n}\rangle\) |
\mathbf{x} = \langle x_{1}, x_{2}, \dots, x_{n}\rangle$ (\bm from the bm package would be better)
|
| \(x \in A\) |
$x \in A$
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| \(|A|\) |
$|A|$
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| \(x \in A\) |
$x \in A$
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| \(A \subset B\) |
$x \subset B$
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| \(A \subseteq B\) |
$x \subseteq B$
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| \(A \cup B\) |
$A \cup B$
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| \(A \cap B\) |
$A \cap B$
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| \(X \sim {\sf Binom}(n, \pi)\) |
$X \sim {\sf Binom}(n, \pi)$ (sf for “slide font”
|
| \(\mathrm{P}(X \le x) = {\tt pbinom}(x, n, \pi)\) |
$\mathrm{P}(X \le x) = {\tt pbinom}(x, n, \pi)$ (tt for “typewriter type”)
|
| \(P(A \mid B)\) |
$P(A \mid B)$
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| \(\mathrm{P}(A \mid B)\) |
$\mathrm{P}(A \mid B)$ (mathrm for “math roman font”
|
| \(\{1, 2, 3\}\) |
$\{1, 2, 3\}$
|
| \(\sin(x)\) |
$\sin(x)$
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| \(\log(x)\) |
$\log(x)$
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| \(\int_{a}^{b}\) |
$\int_{a}^{b}$
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| \(\left(\int_{a}^{b} f(x) \; dx\right)\) |
$\left(\int_{a}^{b} f(x) \; dx\right)$
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| \(\left[\int_{-\infty}^{\infty} f(x) \; dx\right]\) |
$\left[\int_{\-infty}^{\infty} f(x) \; dx\right]$
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| \(\left. F(x) \right|_{a}^{b}\) |
$\left. F(x) \right|_{a}^{b}$
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| \(\sum_{x = a}^{b} f(x)\) |
$\sum_{x = a}^{b} f(x)$
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| \(\prod_{x = a}^{b} f(x)\) |
$\prod_{x = a}^{b} f(x)$
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| \(\lim_{x \to \infty} f(x)\) |
$\lim_{x \to \infty} f(x)$
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| \(\displaystyle \lim_{x \to \infty} f(x)\) |
$\displaystyle \lim_{x \to \infty} f(x)$
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| \(\alpha A\) |
$\alpha A$
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\(\nu N\) |
$\nu N$
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| \(\beta B\) |
$\beta B$
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\(\xi\Xi\) |
$\xi\Xi$
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| \(\gamma \Gamma\) |
$\gamma \Gamma$
|
\(o O\) |
$o O$ (omicron)
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| \(\delta \Delta\) |
$\delta \Delta$
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\(\pi \Pi\) |
$\pi \Pi$
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| \(\epsilon \varepsilon E\) |
$\epsilon \varepsilon E$
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\(\rho\varrho P\) |
$\rho\varrho P$
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| \(\zeta Z\) |
$\zeta Z \sigma \,\!$
|
\(\sigma \Sigma\) |
$\sigma \Sigma$
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| \(\eta H\) |
$\eta H$
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\(\tau T\) |
$\tau T$
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| \(\theta \vartheta \Theta\) |
$\theta \vartheta \Theta$
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\(\upsilon \Upsilon\) |
$\upsilon \Upsilon$
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| \(\iota I\) |
$\iota I$
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\(\phi \varphi \Phi\) |
$\phi \varphi \Phi$
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| \(\kappa K\) |
$\kappa K$
|
\(\chi X\) |
$\chi X$
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| \(\lambda \Lambda\) |
$\lambda \Lambda$
|
\(\psi \Psi\) |
$\psi \Psi$
|
| \(\mu M\) |
$\mu M$
|
\(\omega \Omega\) |
$\omega \Omega$
|
It is possible to define macros to make your mathematics easier to read. Macros are written in text chunks (because they are not R code).
Example: The following text
\newcommand{\intersect}{\operatorname{\cap}}
\newcommand{\union}{\operatorname{\cup}}
\newcommand{\Prob}{\operatorname{P}}
$$\Prob(A \union B) = \Prob(A) + \Prob(B) - \Prob(A \intersect B)$$turns into
\[{\operatorname{P}}(A {\operatorname{\cup}}B) = {\operatorname{P}}(A) + {\operatorname{P}}(B) - {\operatorname{P}}(A {\operatorname{\cap}}B)\]