# Test the LaTeX markdown in this sandbox question!

## Purpose of question

We have $$\\LaTeX\$$ support through MathJax! Now, instead of writing equations like this:

w0 = 1 / sqrt(L * C)


we can write:

$$\\displaystyle \omega_0 = \frac{1}{\sqrt{LC}}\$$

Beautiful! However, TeX has a steep learning curve, and it will take some time to figure out how to use this feature. This question is a sandbox in which to practice its use.

## Documentation

You'll see in the right sidebar, when writing a question, the line:

MathJaX[sic] equations $sin^2\theta$

and a link to generic TeX help. I find that the math mode section is most helpful. The special symbols article is particularly useful:

$$\\$$ \alpha \beta \mu \Omega \omega \theta $$\\$$

Note that not all of TeX is included; you'll get this message if you try to include a module that's not in MathJax, such as Tabular:

$$\\begin{tabular}1 & 2\\3 & 4\end{tabular}\$$

## How did they do that?

You can always get at the source by right-clicking an equation. A MathJax context menu will come up, like the following:

(some versions of MathJax use Show Source menu)

and "Show Math As - TeX Commands" will bring up a window with the source for the equations. Just drop the text contained $between a pair of escaped dollar signs!$ Or, you can $$surround it with two dollar signs for centering.$$

## Begin $$\\LaTeX\$$ Sandbox

The markdown for a question should be identical to what you get from an answer, but I'll leave the rest of this question for testing more TeX in case that assumption is mistaken.

Note: This is a recreated version of the original MathJax sandbox question. At some point, that post evolved to cause crashing in some web browsers, and was deleted.

Some MathJax frequently used here:

Equation in-line: $123$ $$\\rightarrow\$$ $$\123\$$

Equation centered on a separate line: $$123$$ $$\\rightarrow\$$ $$123$$

Fractions: 1/2 $$\\rightarrow\$$ $\frac{1}{2}$ $$\\rightarrow\$$ $$\\frac{1}{2}\$$

Bigger fractions: 1/2 $$\\rightarrow\$$ $\dfrac{1}{2}$ $$\\rightarrow\$$ $$\\dfrac{1}{2}\$$

Something enclosed by full parentheses: (1/2) $$\\rightarrow\$$ $\left(\frac{1}{2}\right)$ $$\\rightarrow\$$ $$\\left(\frac{1}{2}\right)\$$

Exponent: I^2 $$\\rightarrow\$$ $I^2$ $$\\rightarrow\$$ $$\I^2\$$

Exponent: e^-1 $$\\rightarrow\$$ $e^{-1}$ $$\\rightarrow\$$ $$\e^{-1}\$$ ... or $e^{\text{-1}}$ $$\\rightarrow\$$ $$\e^{\text{-1}}\$$

Subscript: t0 $$\\rightarrow\$$ $t_0$ $$\\rightarrow\$$ $$\t_0\$$

Removing the italics from previous: $$\\rightarrow\$$ \text{t}_0 $$\\rightarrow\$$ $$\\text{t}_0\$$ (now omitting \\$ tags for display brevity but they are still required.)

Square Root: sqrt(9) $$\\rightarrow\$$ \sqrt{9} $$\\rightarrow\$$ $$\\sqrt{9}\$$

Cubic Root: ? $$\\rightarrow\$$ \sqrt[3]{27} $$\\rightarrow\$$ $$\\sqrt[3]{27}\$$

Greek symbols: \alpha $$\\alpha\quad\$$ \beta $$\\beta\quad\$$ \gamma $$\\gamma\quad\$$ \delta $$\\delta\quad\$$ \epsilon $$\\epsilon\quad\$$ \varepsilon $$\\varepsilon\quad\$$ \zeta $$\\zeta\quad\$$ \eta $$\\eta\quad\$$ \theta $$\\theta\quad\$$ \vartheta $$\\vartheta\quad\$$ \iota $$\\iota\quad\$$ \kappa $$\\kappa\quad\$$ \lambda $$\\lambda\quad\$$ \mu $$\\mu\quad\$$ \nu $$\\nu\quad\$$ \xi $$\\xi\quad\$$ \omicron $$\\omicron\quad\$$ \pi $$\\pi\quad\$$ \varpi $$\\varpi\quad\$$ \rho $$\\rho\quad\$$ \varrho $$\\varrho\quad\$$ \sigma $$\\sigma\quad\$$ \varsigma $$\\varsigma\quad\$$ \tau $$\\tau\quad\$$ \upsilon $$\\upsilon\quad\$$ \phi $$\\phi\quad\$$ \varphi $$\\varphi\quad\$$ \chi $$\\chi\quad\$$ \psi $$\\psi\quad\$$ \omega $$\\omega\quad\$$ \Gamma $$\\Gamma\quad\$$ \Delta $$\\Delta\quad\$$ \Theta $$\\Theta\quad\$$ \Lambda $$\\Lambda\quad\$$ \Sigma $$\\Sigma\quad\$$ \Upsilon $$\\Upsilon\quad\$$ \Psi $$\\Psi\quad\$$ \Omega $$\\Omega\quad\$$

Comparisons: i < 5 $$\\rightarrow\$$ i\lt 5 $$\\rightarrow\$$ $$\i\lt 5\$$ ... \neq $$\\rightarrow \:\neq\quad\$$ \approx $$\\rightarrow \:\approx\quad\$$ \simeq $$\\rightarrow \:\simeq\quad\$$

Operators: \times $$\\rightarrow \:\times\quad\$$ \pm $$\\rightarrow \:\pm\quad\$$ \cdot $$\\rightarrow \:\cdot\quad\$$ \oplus $$\\rightarrow \:\oplus\quad\$$ \infty $$\\rightarrow \:\infty\quad\$$

Trigonometry: sin(x) $$\\rightarrow\$$ \sin x $$\\rightarrow\$$ $$\\sin x\$$

Logs: nat log(n) $$\\rightarrow\$$ \ln x $$\\rightarrow\$$ $$\\ln x\$$ ... \log_{20}(x) $$\\rightarrow \:\log_{20}(x)\quad\$$

Sum: \sum_{a=1} ^{B} c $$\\rightarrow \sum_{a=1} ^{B} c\$$

Product: \prod_{a=1} ^{B} c $$\\rightarrow \prod_{a=1} ^{B} c\$$

Integral: \int_{0} ^{\infty} x dx $$\\rightarrow \int_{0} ^{\infty} x dx\$$

Limit: \lim_{x \to \infty} $$\\rightarrow \lim_{x \to \infty}\$$

Overline: /nRESET $$\\rightarrow\$$ \overline{\text{nRESET}} $$\\rightarrow\$$ $$\\overline{\text{nRESET}}\$$

Vector: \vec{x} $$\\rightarrow\$$ $$\\vec{x}\$$ also \overrightarrow{x} $$\\rightarrow\$$ $$\\overrightarrow{x}\$$

Sadly there is no siunitx support, so to get the units right, it gets a bit clumsy like this:

3 V $$\\rightarrow\$$ 3~\text{V} $$\\rightarrow\$$ $$\3~\text{V}\$$

The ~ is there to generate the space and as units are written upright and not in italics we need to use \text{unit}

As Massimo Ortolando suggests using \, typesets a smaller space, which is used in the siunitx package to make the combination look more like a single entity:

3 V $$\\rightarrow\$$ 3\,\text{V} $$\\rightarrow\$$ $$\3\,\text{V}\$$

• Yeah, unfortunately siunitx is not supported is any site. For the space, I suggest to use the small space \,, which better represents the fact that the quantity is a single object (siunitx uses this). May 12 '21 at 17:38
• @MassimoOrtolano nice, thanks for that. I incorporated this in my answer and the difference is small but visible. May 12 '21 at 19:04

### MathJax resources on the other stackexchange sites:

meta.SE: Which Sites Use MathJax -- Which Stack Exchange sites use MathJax?

meta.SE: questions tagged MathJax -- https://meta.stackexchange.com/questions/tagged/mathjax?tab=Active

math.SE: MathJax basic tutorial and quick reference -- https://math.meta.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-quick-reference

1. Parentheses

Ordinary symbols () [] make parentheses and brackets $$\(2+3)[4+4]\$$.
Use \{ and \} for curly braces $$\\{\}\$$.

These do not scale with the formula in between,
so if you write (\frac{\sqrt x}{y^3}) the parentheses will be too small: $$\(\frac{\sqrt x}{y^3})\$$.
Using \left(\right) will make the sizes adjust automatically to the formula they enclose:
\left(\frac{\sqrt x}{y^3}\right) is $$\\left(\frac{\sqrt x}{y^3}\right)\$$.

\left and \right apply to all the following sorts of parentheses:
( and ) $$\(x)\$$,
[ and ] $$\[x]\$$,
\{ and \} $$\\{x\}\$$,
| $$\|x|\$$,
\vert $$\\vert x \vert\$$,
\Vert $$\\Vert x \Vert\$$,
\langle and \rangle $$\\langle x \rangle\$$,
\lceil and \rceil $$\\lceil x \rceil\$$,
\lfloor and \rfloor $$\\lfloor x \rfloor\$$.
\middle can be used to add additional dividers.

\left[\frac{\sqrt x}{y^3}\right] is $$\\left[\frac{\sqrt x}{y^3}\right]\$$.

There are also invisible parentheses, denoted by .:
\left.\frac12\right\rbrace is $$\\left.\frac12\right\rbrace\$$.

If manual size adjustments are required: \Biggl(\biggl(\Bigl(\bigl((x)\bigr)\Bigr)\biggr)\Biggr) gives $$\\Biggl(\biggl(\Bigl(\bigl((x)\bigr)\Bigr)\biggr)\Biggr)\$$.

Fractions

\frac{a+1}{b+1} is $$\\frac{a+1}{b+1}\$$
{a+1\over b+1} is $$\{a+1\over b+1}\$$

Roots

Use sqrt, which adjusts to the size of its argument:
\sqrt{x^3} $$\\sqrt{x^3}\$$
\sqrt[3]{\frac xy} $$\\sqrt[3]{\frac xy}\$$
\left({\frac qr}\right)^{1/2} $$\\left({\frac qr}\right)^{1/2}\$$

\operatorname{myfunction}(x) $$\\operatorname{myfunction}(x)\$$

Matrices:

$$G_{\text{MNA}} = \begin{bmatrix} g_1 & -g_1 & \cdots \\ -g_1 & g_1 & \cdots \\ \vdots & \vdots & \ddots \end{bmatrix}$$


$$G_{\text{MNA}} = \begin{bmatrix} g_1 & -g_1 & \cdots \\ -g_1 & g_1 & \cdots \\ \vdots & \vdots & \ddots \end{bmatrix}$$

Cases:

$$I_\text{LED} = \begin{cases} (V - V_F) / R;& V > V_F\\ 0;&V < V_F\end{cases}$$


$$I_\text{LED} = \begin{cases} (V - V_F) / R;& V > V_F\\ 0;&V < V_F\end{cases}$$

Here's a resource I found useful

https://arachnoid.com/latex/

(be sure to click the "mathjax" radio button, as it has other latex renderings too)