Plain-text notes are convenient until an explanation needs a fraction, integral, matrix, or Greek symbol. Lutin Notes and Documents combine portable Markdown with LaTeX-style mathematical notation rendered by KaTeX.
That means a formula can stay beside the explanation, links, examples, and questions that give it context. You do not need to paste an equation as an image or keep the maths in a separate document.
Write an inline formula
Use single dollar signs when a formula belongs inside a sentence:
The area of a circle is $A = \pi r^2$.
Lutin renders the content between the delimiters as inline mathematics. The
source remains Markdown, so the equation can round-trip back to the same
$...$ notation when the document is saved.
Other examples:
The sequence converges when $|r| < 1$.
The derivative of $x^n$ is $nx^{n-1}$.
For a right triangle, $a^2 + b^2 = c^2$.
Keep the delimiters close to the formula. Whitespace immediately inside the dollar signs is treated as text rather than an inline equation.
Write a display equation
Use double dollar signs for an equation that should occupy its own block:
$$
E = mc^2
$$
Display maths must begin at the start of a block. This prevents dollar signs in ordinary prose from unexpectedly turning the rest of a paragraph into a large equation.
A longer example:
$$
\int_0^1 x^2\,dx = \left[\frac{x^3}{3}\right]_0^1 = \frac{1}{3}
$$
Useful LaTeX patterns
Here are a few common patterns for study notes:
| Result | Write |
|---|---|
| Superscript | $x^2$ |
| Subscript | $a_n$ |
| Fraction | $\frac{a}{b}$ |
| Square root | $\sqrt{x}$ |
| Greek letter | $\alpha + \beta$ |
| Sum | $\sum_{i=1}^{n} i$ |
| Integral | $\int_a^b f(x)\,dx$ |
| Vector | $\mathbf{v}$ |
For a matrix, use a display block:
$$
A = \begin{bmatrix}
1 & 2 \\
3 & 4
\end{bmatrix}
$$
Keep dollar signs literal
Lutin's formula parser is designed to leave ordinary prices such as $50 as
text. If a pair of dollar signs could look like deliberate formula syntax,
escape the symbol with a backslash:
The total is \$100.
Dollar signs inside inline code or fenced code blocks remain code:
Use `$HOME` to refer to the home directory.
This lets programming notes and mathematical notes use the same Markdown document without treating every dollar sign as a formula.
Ask Lutin to format an equation
If you know the maths but not the LaTeX command, ask for only the notation you need:
- "Write this equation as inline LaTeX."
- "Convert these steps into one display equation."
- "How do I write this matrix in LaTeX?"
- "Fix the syntax without changing the equation."
- "Explain what each symbol means below the formula."
Check that the formatted expression still represents your intended equation. Correct syntax cannot make incorrect mathematics true.
Keep equations connected to meaning
A page of formulas is difficult to revise if it no longer says when or why each one applies. Give every important equation a small amount of context:
- State what the formula describes.
- Define unfamiliar variables.
- Add the conditions under which it applies.
- Work through one example.
- Record the source or course section.
- Add one question that tests when to use it.
For a broader workflow, see How to Write Better Study Notes with Lutin and How to Learn Math with Lutin Without Skipping the Thinking.
KaTeX is not a complete LaTeX compiler
Lutin supports mathematical notation rendered by KaTeX. It is not a full LaTeX document environment: packages, page layouts, bibliographies, and arbitrary LaTeX documents are outside this feature's scope.
Use Lutin for equations inside Markdown Notes and Documents. Use a dedicated LaTeX editor when you need to compile a complete paper, thesis, or publication template.
Download Lutin for macOS and keep readable equations beside the notes that explain them.