The LaTeX command for indicator function (𝟙) is \mathds{1} (indicator function / characteristic function).
\mathds{1}Writing a paper? The table generator and the BibTeX cleaner are one click away, no account.
| Command | Package | Use it when |
|---|---|---|
\mathds{1} recommended | dsfont | The usual choice: a crisp vector double-struck 1. |
\mathbbm{1} | bbm | Same look, but bbm ships bitmap (Type 3) fonts, which can look blurry in PDF viewers. |
\mathbf{1} | none | A bold 1, common in probability texts; needs no package. |
Write \mathds{1} inside math mode, that is between $…$ for inline math or in a \[ … \] or equation block for display math. This symbol needs the dsfont package, so add \usepackage{dsfont} to your preamble.
$\mathds{1}_{\{X > 0\}}$Open this example in the live preview: it renders as you type, with no compiler and no signup.
\mathbb{R} (ℝ): real numbers\mathbb{N} (ℕ): natural numbers\mathcal{N} (𝒩): normal / Gaussian distribution\mathbb{E}\mathbb{P}\operatorname{Var}\operatorname{Cov}\operatorname{Cor}\mathcal{N}\mathrel{\perp\!\!\!\perp}\xrightarrow{d}\xrightarrow{p}\xrightarrow{a.s.}\overset{\text{iid}}{\sim}Statistics and probability symbols in LaTeX: the full table or search all 350+ LaTeX symbols.
Use \mathds{1} in math mode after adding \usepackage{dsfont} to your preamble. For example, $\mathds{1}_{\{X > 0\}}$.
It comes from the dsfont package: add \usepackage{dsfont} to your preamble.
\mathbb{1} with amssymb does not give a double-struck one: the AMS blackboard-bold font only contains capital letters, so pdfLaTeX prints the wrong glyph. KaTeX and MathJax do draw it, which is why the mistake spreads through web snippets.