Test the new \$LaTeX\$ markdown in this Sandbox question!

Question

Purpose of question

We now 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}\$

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:

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

This question should be community wiki (No one should get rep from it, and it should be easy to edit), so you can also see the source that way.

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.

Answer 1

Entering Units:

\$Because TeX just jams everything together\$,
\$Because TeX just jams everything together\$
...in order to use units well, you need to use the power of the \text{}

e.g.:

ugly:

$$P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150 volts)^2}{4 \times 10 k\Omega} = 9/16 watts$$ $$P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150 volts)^2}{4 \times 10 k\Omega} = 9/16 watts$$

less ugly:

$$P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150 \text{ volts})^2}{4 \times 10\text{ k}\Omega} = 9/16 \text{ watts}$$ $$P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150 \text{ volts})^2}{4 \times 10\text{ k}\Omega} = 9/16 \text{ watts}$$

I don't really like having to put the \Omega outside of the text though, but if it's inside, then it doesn't parse it...

alternative:

$$P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150\ \mathrm{volts})^2}{4 \times 10\ \mathrm{k\Omega}} = 9/16\ \mathrm{watts}$$ $$P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150\ \mathrm{volts})^2}{4 \times 10\ \mathrm{k\Omega}} = 9/16\ \mathrm{watts}$$

Using \mathrm instead of \text makes commands like \Omega work, but means that spaces must be written as \ .

(The technical explanation is that \text switches the TeX parser from "math mode" to "text mode", where the parsing works differently, while \mathrm simply changes the font while staying in math mode.)

Ps. {\rm watts} will also work instead of \mathrm{watts}. Those two commands are basically equivalent, just with different syntax. (\rm is a basic TeX command, while \mathrm is LaTeX. That's pretty much the only difference.)

Answer 2

Subscripts and Superscripts

Easy enough:

• \$R_{max} = 42\$
  • R_{max} = 42
    
    
• \$e^{i\pi} = -1\$
  • e^{i\pi} = -1

What if you want \$R_{max}\$ squared?

• \$R_{max}^2\$
  • R_{max}^2

perhaps not what you wanted, with the subscript and superscript lining up. If you want the superscript to start at the end of the subscript you can jam and empty field(?) to separate them, e.g.:

• \$R_{max}{}^2\$
  • R_{max}{}^2

(from here)

Answer 3

\$\triangledown \cdot E = \frac{\rho}{\epsilon_0}\$

\$\triangledown \cdot B = 0\$

\$\triangledown \times E = - \frac{\partial B}{\partial t}\$

\$\triangledown \times B = \mu_0 J + \mu_0 \epsilon_0 \frac{\partial E}{\partial t}\$

Pretty sweet...

Answer 4

And if you want to draft/sandbox your MathJax equations on your own PC, Julian Bucknall has a blog post here on how to create an HTML page to do this. It works a treat. Just remember you don't need the \$ delimiters.

Answer 5

Here's my try:\$50 \mbox{ }\Omega\$. But that was too short.

Answer 6

\$\LaTeX\$ is superset of \$\TeX\$

Answer 7

$100 <- Testing dollar

Your transformer will convert 120\$V_{ac}\$ to 12\$V_{ac}\$. So you'll need to regulate it to 5\$V_{dc}\$.

• \$I_{ce}\$ = \$I_{be}\$ * HFE

• \$V_{ceo}\$ \$I_{c}MAX\$

• ASCII:
  16 - log((5 - 0)/(5 - 4))/log(2) = 13.68

• TeX:
  \$16 - \frac{log\frac{(5 - 0)}{(5 - 4)}}{log 2} = 13.68\$

• \$I_{F_{max}} = 30mA\$

• \$V_{F_{typ}} = 1.7V\$
• \$V_{F_{max}} = 2.1V\$
• \$V_{R_{max}} = 5V\$

Answer 8

This chip costs \$$1.21\$, but an alternative is only \$$0.88\$.

One complaint about using dollar signs is that prices are used too often in electronics questions. Can we at least change it to double-dollar on each end?

Using normal $ signs is no longer a problem. The above sentence looked like this when we used `$ .. $` as the delimiters:

This chip costs \$1.21, but an alternative is only \$0.88.

but this has been fixed. Just use normal dollar signs:

This chip costs $1.21, but an alternative is only $0.88.

If something funny happens to your prose, you've probably got an unmatched delimiter in your equations somewhere. Make sure that \$ only appears around equations.

Answer 9

Need a new sandbox -- one without cat poop. (Testing comments w/o bugging authors.)

\$\infty\$

Answer 10

Tables

Inline math doesn't work for tables: \$begin{array}...\end{array}\$ produces the array on one line:

Apparently, something's changed since this answer was originally written, and tables now work just fine in inline math:

\$ \begin{array}{ccc}x&S(n,x)&x^n \log\left(\frac{x}{x-1}\right)\\-5&-1780484.04&-1780483.95\\-3&-16987.42&-16987.34\\2&709.598&709.783\\ 4&301656.39&301656.52\\6&1.102428722 \times 10^7&1.102428734 \times 10^7\end{array} \$

For arrays, equation arrays, matrices, piecewise equations, aligned equations, and other multi-line constructs, you no longer need to use the displayed math $$..$$ delimiter set, which places the equation on its own line(s):

$$ \begin{eqnarray} f_p(x) & = & \sum_{j=0}^{n} c_j \phi(||x - x_j||) \\ & = & \sum_{j=0}^{n} c_j \phi_j(x) \\ & = & c_0 \phi_0(x) + c_1 \phi_1(x) + \cdots + c_n \phi_n(x) \end{eqnarray} $$

Answer 11

And you can use Unicode when typing your maths:

$$ A = πr^2 $$

A better way of doing what he did:

$$ P_{max} = \frac{V_{max}{}^2}{4R_{sink}} = \frac{(150 \text{ volts})^2}{4 \times 10\text{ kΩ}} = 9/16 \text{ watts} $$

$$ P_{max} = \frac{V_{max}{}^2}{4R_{sink}} =
   \frac{(150 \text{ volts})^2}{4 \times 10\text{ kΩ}} = 9/16 \text{ watts} $$

Answer 12

Nested dfracs: \$ \dfrac{ \dfrac{\alpha \beta ^{j2 \pi f t}}{j \omega} }{ \dfrac{\gamma \delta}{\Omega \Phi} } \$ these are meant to create inline equations without resizing them to the size of a single line of text. The line is in effect streched to contain the full equation becoming much higher :)