Maths in notes

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Formulas are written in LaTeX and rendered by KaTeX. Every command KaTeX supports works, except those that add links, images or HTML, such as \href and \includegraphics, which show in red. At the start of a line, $$x^2$$, $$$x^2$$$ or \[x^2\] makes a block. Inside a line of text, $$x^2$$ and \(x^2\) make a formula in the line, and so does $x^2$ once you type a space or punctuation after it. /math inserts a block through a dialog with a live preview and a symbol palette instead, and clicking a formula opens it again for editing. Right-click or long-press a formula to copy its LaTeX or a picture of it. In imported Markdown, $...$ is a formula in the line. $$...$$ is a block when it has a line to itself or sits between two $$ lines, and a formula in the line anywhere else.

Chemistry comes from mhchem: \ce{H2O}, \ce{CO2 + C -> 2CO}, \ce{SO4^2-} and quantities such as \pu{123 kJ//mol}.

Physics notation comes from part of the LaTeX physics package:

• derivatives: \dv{f}{x}, \dv[2]{y}{t}, \pdv{f}{x}, \pdv{f}{x}{y}, and \dd{x} for the d at the end of an integral
• brackets that grow with what they hold: \abs{x}, \norm{v}, \qty(\frac{a}{b}), \qty[x] and \qty|x|. \abs*{x} and \norm*{v} keep them at text size.
• vectors: \vb{F} in bold, \va{r} with an arrow, \vu{n} with a hat, \vdot, \cross, \grad, \divergence, \curl and \laplacian
• quantum mechanics: \bra{\psi}, \ket{\phi}, \braket{\psi}{\phi}, \expval{H}, \mel{n}{H}{m} and \comm{A}{B}
• also \eval{x^2}_0^1, \order{x^2}, \mqty(a & b \\ c & d) for a matrix, and \Tr, \rank, \erf and \Res

\div stays division, as in plain LaTeX.

Your own commands work too: \newcommand, \renewcommand, \def and \DeclareMathOperator. A command defined in a formula applies to that formula and to every formula after it in the same note, as in a LaTeX document, so \newcommand{\R}{\mathbb{R}} near the top serves the whole note. Moving or deleting the definition changes the formulas below it. Commands never carry over to another note. A formula on a study set card or in a test question stands alone: a command it defines works only inside it.

Formulas in equation, align, gather and alignat are numbered (1), (2), (3) down the note; the starred forms, such as align*, are not. Give a line \label{name}, and \eqref{name} in any formula shows its number, which follows when equations above it are added or removed. \tag{A} gives a line its own label instead of a number, and \nonumber leaves a line out. A label no formula has shows as (??). Copying, exporting and the AI still see the LaTeX as you wrote it, \label and \eqref included.

Not supported yet: multline, \cancelto, siunitx (\SI) and drawing packages such as TikZ. A command KaTeX doesn't know shows in red.