Left arrow (←) in LaTeX
\leftarrow typesets a leftward arrow ←, the mirror image of \rightarrow, used for assignment, reverse mappings and labelling directions in diagrams.
LaTeX command
\leftarrowNot the symbol you meant? Draw it to find the command →
\leftarrow draws a single arrow pointing left. It appears most often in assignment statements borrowed from computer science and pseudocode, where means 'a is assigned the value of , reading opposite to an equals sign which merely states two things are equal rather than describing an action.
It also appears wherever a relationship or process naturally runs in the opposite direction to the default left-to-right reading, for instance labelling a reverse map, an inverse process, or the left-pointing half of a diagram where \rightarrow is used for the other direction.
The double-line version \Leftarrow (⇐) is the logical counterpart, used for a one-directional implication written backwards, meaning the same as . Combined with \Rightarrow, it also builds \Leftrightarrow (⇔), an alternative to \iff for a two-way equivalence.
Other forms
\Leftarrowdouble (⇐)Examples
$a \leftarrow b$assignment, a takes the value of b (algorithm pseudocode)
$Q \Leftarrow P$the double-line form, equivalent to
$P \Leftrightarrow Q$built from \Leftarrow and \Rightarrow, an alternative to \iff
$g^{-1} : B \leftarrow A$labelling an inverse map running the opposite way
Tips and common mistakes
- Use
\leftarrowfor assignment in pseudocode (), keeping it visually distinct from = which states equality rather than performing an action. - Pair
\leftarrowwith\rightarrowwhen labelling two opposite processes or maps in the same diagram, so the direction is unambiguous at a glance. - Use the double-line
\Leftarrowonly for logical implication written in reverse; for a plain leftward function or mapping arrow, the single-line\leftarrowis correct. - For a longer leftward arrow, for example over a wide label, use
\longleftarrowinstead of\leftarrow. \Leftrightarrowand\iffrender the same double-headed arrow for logical equivalence;\iffadditionally adds a little breathing space around it in running text.
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What does \leftarrow mean?
It typesets a plain leftward arrow (←). Its most common use is assignment in algorithms and pseudocode, meaning 'assign the value of b to , though it also labels reverse maps and left-pointing relationships in diagrams.
What is the difference between \leftarrow and \Leftarrow?
\leftarrow is a single-line arrow, typically used for assignment or a plain leftward mapping. \Leftarrow is the double-line logical arrow, used for implication written in reverse, meaning P implies Q.
How do I write assignment in LaTeX pseudocode?
Use \leftarrow between the variable and its new value, as in + 1, which is the standard notation in algorithm pseudocode, distinct from the equals sign.
Is there a longer version of \leftarrow?
Yes, \longleftarrow produces a stretched leftward arrow, useful for wide labels or diagrams, matching \longrightarrow on the other side.