[latex]

\quicklatex{color=”#000000″ size=100}

{A^{d}\alpha}\oint_r u_i \cdot T!}

[/latex]

Yesterday, I published a post about opamps here on the blog. This post utilized a new feature here at Adafruit: rendered LaTeX equations. For those that are unfamiliar, LaTeX is a markup language for the TeX system, originally developed by legendary computer scientist Donald Knuth. LaTeX (pronounced “Lay-Tek”), is used by scientists, educators and engineers around the world to format equations so that they look nice and neat, and are easy to read.

About a month ago, in the course of originally drafting that opamp article, I started looking around at LaTeX plugins for WordPress. There are several of these available. All of them have their strengths and weaknesses, but eventually I settled on WP-QuickLaTeX by Pavel Holoborodko, Dmitriy Gubanov and Kim Kirkpatrick.

WPQL supports automatic equation numbering, has built in tikz and pgfplots support, can render alpha-channel PNGs, and supports LaTeX markup in blog comments, which means that the conversation can go both ways. TeX and LaTeX have been around a long time, so there is information all over the place about how to use it, but here are a few tutorials (1, 2)

What this means for you is that we can more easily do technical posts on the blog, and drop transfer functions like this:

[latex]

\begin{equation}

\frac{V_o}{V_i} = \frac{(g_m R_{g})^2} { (s C R_f)^2 + 2 s C R_{g} g_m + (R_{g} g_m)^2}

\end{equation}

[/latex]

Or plots like this:

[latex]

\begin{tikzpicture}

[+preamble]

\usepackage{pgfplots}

\pgfplotsset{compat=newest}

[/preamble]

\begin{axis}

\addplot3[surf,domain=0:360,samples=40] {sin(2*x)*cos(y)};

\end{axis}

\end{tikzpicture}

[/latex]

We’re super-excited to have this new functionality here, and we hope you are too. **If you want to take LaTeX for a test drive in the comments, you can use the ![latex] and [/latex] tags at the beginning and end of your LaTeX statements.** If you want to make sure your code works before you post it, you can test it at quicklatex.com (include the preamble under “choose options” — thanks, zerth!)

Try it out now!

w00t!

[latex]i_t \cdot re^{a}lly \times \omega0rk_{s}![/latex]

hmmm…

\[ \cos(\theta + \phi) = \cos \theta \cos \phi

– \sin \theta \sin \phi \]

$sigh$

Oops, missed that last part about latex tags being needed…

[latex]

\[ \cos(\theta + \phi) = \cos \theta \cos \phi

– \sin \theta \sin \phi \]

[/latex]

Hmm…

[latex]\int_-\infty^\infty \! e^{-x^2} \mathrm{d} x = \sqrt{\pi}[/latex]

hrm…

[latex]

[samepage, fontsize=, frame=single, label=Sierpinski Sieve] def sierpinski(expr a, b, n) = if n = 0: fill a–(b rotatedabout(a, 60))–b–cycle; else: sierpinski(a, 0.5[a,b], n-1); sierpinski(0.5[a,b], b, n-1); sierpinski(0.5[a,b rotatedabout(a, 60)], 0.5[a rotatedabout(b, -60),b], n-1); fi; enddef;

[/latex]

@zerth: you have to tell it what packages to use or it cannot render graphics.

[latex]

e^{i \pi} – 1 = 0

[/latex]

Hmmm. I just looked at my post. The latexpage order apparently didn’t work. Do I need to do a slash-close order at the end?

I fixed the Euler equation so that it would display correctly. We seem to be having a problem with latexpage in the comments. In the meantime, you can wrap your equations in the ![latex] and [/latex] tags and it will render correctly.

[latex]

\begin{tikzpicture}

[+preamble]

\usepackage[usenames,dvipsnames,pdftex]{xcolor}

\usepackage{tikz,ifthen}

[/preamble]

\coordinate (A) at (0,0);

\coordinate (B) at (-60:12cm);

\coordinate (C) at (240:12cm);

\foreach \density in {20,30,…,160}{%

\draw[fill=MidnightBlue!\density] (A)–(B)–(C)–cycle;

\path

(A) coordinate (X)

— (B) coordinate[pos=.15](A)

— (C) coordinate[pos=.15](B)

— (X) coordinate[pos=.15](C);

}

\end{tikzpicture}

[/latex]

whoa!

Okie, try again.

[latex]

[preamble]

\usepackage{tikz}

\usetikzlibrary{lindenmayersystems}

\usetikzlibrary[shadings]

[/preamble]

\pgfdeclarelindenmayersystem{Koch curve}{

\rule{F -> F-F++F-F}}

\pgfdeclarelindenmayersystem{Sierpinski triangle}{

\rule{F -> G-F-G}

\rule{G -> F+G+F}}

\pgfdeclarelindenmayersystem{Fractal plant}{

\rule{X -> F-[[X]+X]+F[+FX]-X}

\rule{F -> FF}}

\pgfdeclarelindenmayersystem{Hilbert curve}{

\rule{L -> +RF-LFL-FR+}

\rule{R -> -LF+RFR+FL-}}

\begin{tikzpicture}

\shadedraw[shading=color wheel]

[l-system={Koch curve, step=2pt, angle=60, axiom=F++F++F, order=4}]

lindenmayer system — cycle;

\end{tikzpicture}

[/latex]

gah, stupid shift key. Last try.

[latex]

[preamble]

\usepackage{tikz}

\usetikzlibrary{lindenmayersystems}

\usetikzlibrary[shadings]

[/preamble]

\pgfdeclarelindenmayersystem{Koch curve}{

\rule{F -> F-F++F-F}}

\pgfdeclarelindenmayersystem{Sierpinski triangle}{

\rule{F -> G-F-G}

\rule{G -> F+G+F}}

\pgfdeclarelindenmayersystem{Fractal plant}{

\rule{X -> F-[[X]+X]+F[+FX]-X}

\rule{F -> FF}}

\pgfdeclarelindenmayersystem{Hilbert curve}{

\rule{L -> +RF-LFL-FR+}

\rule{R -> -LF+RFR+FL-}}

\begin{tikzpicture}

\shadedraw[shading=color wheel]

[l-system={Koch curve, step=2pt, angle=60, axiom=F++F++F, order=4}]

lindenmayer system — cycle;

\end{tikzpicture}

[/latex]

For anyone who wants to proof before posting: http://quicklatex.com/

Although you have to put your preamble in under “choose options” and if you mistype your WP tags, it won’t tell you.

Also, I’m pretty sure it’s a plus in the Euler equation. [latex]e^{i*\pi} + 1 = 0[/latex]

Harry,

I just checked my hand written notes, and you are correct. I have trouble using keyboards since they haven’t been invented yet.

Regards,

Leonhard

[latex]

\begin{split*}

&\left( \epsilon \frac{d}{d\zeta} – \frac{d^{2}}{d\zeta^{2}} \right) (\bar{T}_{1}(\zeta) +\epsilon \bar{T}_{2}(\zeta) +…)\\

& = \epsilon^{2} \mathfrak{D} ( \bar{T}_{b} – \bar{T}_{1} (\zeta) -\epsilon \bar{T}_{2} (\zeta)+… )exp \left( -\frac{1}{\epsilon ( \bar{T}_{1}(\zeta) + \epsilon\bar{T}_{2}(\zeta)+… ) } \right)

\end{split*}

[\latex]

Yay, part of the assignment I’ve been working on for the last couple of days! Basically trying to write an equation for flame speed and thickness… (hopefully not the only non-EE here)