Notation self-test

Everything on this page renders through the real pipeline. Two rows differ deliberately from the historical HTML reference: the \dddot row now resolves via a macro, and the old \textmu row is replaced by a literal\text{µm}.

This fragment renders through the real MDX -> remark-math -> rehype-katex pipeline, so every row below is exactly what a lesson would get. It is the notation contract, executed.

Units go through \SI

Rest energy of the electron: $\SI{511}{keV}$. Standard gravity: $\SI{9.81}{m/s^2}$. Avogadro constant as a symbol: $\SI{6.022}{mol^{-1}}$.

Because writing a unit means typing \SI, a bare italic unit is not a mistake you can make by accident.

The differential is \dd

A derivative: ${\dfrac{\dd y}{\dd x}}$. An integral: $\int f(x)\,\dd x$. The upright-vs-italic differential decision lives in one macro, not in prose.

\dddot works via the macro

KaTeX ships \dot and \ddot but not \dddot. The macro supplies it: $\dddot{x}$ (jerk, Newton notation). Past two dots Newton’s notation is unreadable, which is the whole reason Leibniz and Lagrange exist, so this row exists to prove the macro resolves, not to endorse the notation.

Upright lowercase Greek and the micro sign

KaTeX has no upright lowercase Greek (issue #564); \mathrm{\mu} renders italic anyway. For a micrometre we use the literal Unicode micro sign inside \text{}: $\text{µm}$. It renders from the system font, not KaTeX’s, so the typography clashes slightly. That is accepted; there is no better option. (\textmu does not exist in KaTeX, which is why this row uses the literal glyph.)

Inline fractions use \dfrac

Plain inline \frac renders cramped: $\frac{1}{2}mv^2$. The same fraction with \dfrac is legible inline: ${\dfrac{1}{2}mv^2}$.

Brace-suppressed line breaks

KaTeX auto-breaks inline math after a relation, so $F = ma$ can wrap at the =. Wrapping the whole thing in braces suppresses it: ${F = ma}$.

A display equation, for reference

Live numbers via sci() (Intl, not KaTeX)