Mathematics

texish has a TeX math mode set in Latin Modern Math through an OpenType MATH table. Math is delimited by dollar signs: a single $…$ for inline math, a doubled $$…$$ for a display centered on its own line.

Inline, like $a^2 + b^2 = c^2$, or displayed:
$$ e^{i\pi} + 1 = 0. $$

To render math on a web page (KaTeX-style, in the browser), see Rendering in the Browser.

Scripts

^ and _ attach a superscript and subscript to the preceding atom. Braces group a multi-token script.

$x^2$    $a_i$    $x_i^2$    $e^{-x^2}$    $\sum_{i=1}^{n}$

Fractions and radicals

$\frac{a}{b}$            % a fraction
$a \over b$              % the infix form
$\sqrt{2}$               $\sqrt[3]{x}$        % square and higher roots

Big operators and limits

$\sum_{i=1}^{n} i$       $\int_0^\infty f$
$\sum\limits_{i=1}^{n}$  % force stacked limits in inline style

In display style, the limits of \sum, \prod, and the like stack above and below by default.

Delimiters

\left and \right grow a delimiter to the height of the material between them.

$\left( \frac{a}{b} \right)$
$\left[ \sum_{i} x_i \right]$

Accents

$\hat{x}$    $\vec{v}$    $\widehat{abc}$

Roman text and the math alphabets

\text sets upright words inside a formula, through the normal text path:

$V = \text{volume}$        $x \text{ for } x > 0$

The math alphabets remap their letters into the corresponding Unicode Mathematical Alphanumeric block, so the same letter can be set in any of the standard math typefaces:

$\mathbb{N} \subset \mathbb{Z} \subset \mathbb{R} \subset \mathbb{C}$
$\mathcal{F} : \mathfrak{A} \to \mathfrak{B}$        $\mathbf{x} \in \mathbb{R}^n$

A character an alphabet has no shape for — a digit in italic or fraktur, say — falls back to its ordinary form.

Phantoms and smash

A phantom reserves the size of its argument without printing it; \smash does the opposite, printing the argument but reporting zero height and depth. They line things up that would not otherwise align.

$a \phantom{=} b$           % a gap exactly as wide as "="
$\smash{\frac{p}{q}} + r$   % a fraction that no longer spreads the line's spacing

Matrices

$\matrix{ a & b \cr c & d }$       % unbracketed
$\pmatrix{ a & b \cr c & d }$      % parentheses
$\bmatrix{ a & b \cr c & d }$      % brackets
$\cases{ x & if positive \cr -x & otherwise }$

Arrows and relations

Alongside \to / \rightarrow and the basic arrows, the long arrows and the equilibrium harpoon are available as relations:

$\longrightarrow$   $\longleftarrow$   $\longleftrightarrow$   $\longmapsto$
$\rightharpoonup$   $\rightleftharpoons$

Spacing

The TeX math-space commands insert a rigid space scaled to the font (a mu is 1/18 em):

$f(x)\,dx$        $a\;b$        $\int\!f$

Displayed equations with numbers

\eqno sets an equation number flush right on a display line.

$$ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \eqno(1) $$