Long Maps To in LaTeX (\longmapsto)

Where it is used

Draws a long barred arrow mapping an element to its image, for wider expressions than \mapsto.

\longmapsto gives more room when the input or output is long, as in (x, y) \longmapsto x^2 + y^2, or when you want the element rule to line up with a \longrightarrow above it. It reads the same as \mapsto and should be paired with \to or \longrightarrow on the line that states the domain and codomain. The fixed length means a label above still needs \overset. Using it consistently in displayed function definitions gives a clean two-line look.

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\begin{document}
Long Maps To: $\longmapsto$

\[ \phi : V \longrightarrow V^{*}, \quad v \longmapsto \langle v, \cdot \rangle \]
\end{document}

Related symbols

• Northeast Arrow\nearrow
• Maps To\mapsto
• Hook Left Arrow\hookleftarrow
• Up Down Arrow (Double)\Updownarrow
• Hook Right Arrow\hookrightarrow
• Long Left Right Arrow (Double)\Longleftrightarrow

Frequently asked questions

How do I write Long Maps To in LaTeX?

Type \longmapsto in math mode, for example $\phi : V \longrightarrow V^{*}, \quad v \longmapsto \langle v, \cdot \rangle$. It works in plain LaTeX without loading any package.

Which package do I need for \longmapsto?

None. \longmapsto is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \longmapsto in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\longmapsto$ in running text. If you only need the glyph in text, paste the Unicode character ⟼ instead (with XeLaTeX or LuaLaTeX and a font that has it).