The LaTeX command for xleftarrow (←) is \xleftarrow{f} (labeled left arrow).
\xleftarrow{f}Writing a paper? The table generator and the BibTeX cleaner are one click away, no account.
Write \xleftarrow{f} inside math mode, that is between $…$ for inline math or in a \[ … \] or equation block for display math. This symbol needs the amsmath package, so add \usepackage{amsmath} to your preamble.
Arrows are relations in LaTeX, so \xleftarrow{f} gets the same thick spacing as an equals sign. With unicode-math under XeLaTeX or LuaLaTeX, typing ← in a formula gives the same symbol.
$A \xleftarrow{f} B$Open this example in the live preview: it renders as you type, with no compiler and no signup.
\rightharpoondown\leftrightharpoons\rightleftharpoons\dashrightarrow\circlearrowleft\circlearrowright\xrightarrow{f}\longrightarrow\longleftarrow\Longrightarrow\to\leftarrow\rightarrow\leftrightarrowArrows in LaTeX: the full table or search all 350+ LaTeX symbols.
Use \xleftarrow{f} in math mode after adding \usepackage{amsmath} to your preamble. For example, $A \xleftarrow{f} B$.
It comes from the amsmath package: add \usepackage{amsmath} to your preamble.