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:
$$ e^{i\pi} + 1 = 0. $$

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 calligraphic letters

\text sets upright words inside a formula; \mathcal sets calligraphic capitals.

$V = \text{volume}$        $\mathcal{C}$        $\mathcal{P}(S)$

Matrices

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

Displayed equations with numbers

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

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