mathtools in Scissor LaTeX

The mathtools package works in Scissor LaTeX: \DeclarePairedDelimiter, the colon relations such as \coloneqq, dcases, cases*, the starred matrices, \prescript and \shortintertext work; \splitfrac, multlined and a few rarer commands show a red formula.

What the package does

mathtools builds on amsmath. It fixes a few spacing details and adds tools: colon relations such as :=, zero-width boxes (\mathclap), more extensible arrows, brackets above and below, dcases, matrices with column alignment, and \DeclarePairedDelimiter for brackets that grow on request.

It loads amsmath for you, so \usepackage{mathtools} is enough.

What works here

Examples

Definitions with \coloneqq, and a long label under a brace kept narrow with \mathclap:

\coloneqq and \mathclap

LaTeXPreamble: \usepackage{mathtools}CopyOpen in editor (opens in a new tab)

f(x) \coloneqq x^2 + 44,
\qquad
\underbrace{a_1 + a_2 + \dots + a_n}_{\mathclap{\text{all the terms of the sequence}}}

Extensible arrows and brackets:

A \xRightarrow{\text{proof}} B \xmapsto{\;g\;} C
\qquad
\overbracket{x + y}^{\text{sum}} \cdot \underbracket{u - v}_{\text{difference}}

\DeclarePairedDelimiter defines brackets: \abs{x} keeps them small, \abs*{x} lets them grow and \abs[\Big]{x} sets their size:

\documentclass{article}
\usepackage{mathtools}
\DeclarePairedDelimiter{\abs}{\lvert}{\rvert}
\begin{document}
\[ \abs{x - 44} < 1, \qquad \abs*{\frac{a}{b}} \le 1, \qquad \abs[\Big]{y} \]
\end{document}

For a piecewise function with fractions in display size, use dcases:

g(x) =
\begin{dcases}
  \frac{1}{x} & x > 0 \\
  0            & x \le 0
\end{dcases}

Compatibility

• From a TeX installation to here: documents typeset with the same numbers; only the few commands marked as not supported above show a red formula.
• From here to a TeX installation: documents compile there unchanged.

The full manual is on CTAN: ctan.org/pkg/mathtools. See also amsmath and Your own commands with \newcommand.

Every example on this page is typeset by Scissor LaTeX when the site is built. Last updated 2026-11-07.