7

Consider:

Enter image description here

I would like to know the LaTeX command for the symbol above. I searched for it online and tried Detexify, but I could not find it.

3 Answers 3

9
\documentclass{article}
\usepackage{bbm}
\begin{document}
$\mathbbm{i}$
\end{document}

enter image description here

One drawback, of course is that the bbm fonts are bitmapped. There is a scalable alternative with the STIX fonts, but it looks slightly different.

\documentclass[border=10]{standalone}
\usepackage{amsmath}

\DeclareFontEncoding{LS1}{}{}
\DeclareFontSubstitution{LS1}{stix}{m}{n}

\newcommand{\bbi}{\text{\usefont{LS1}{stixbb}{m}{n}i}}

\begin{document}

$\bbi$
\end{document}

enter image description here

3
  • May I know why you not recommend about the \mathbb tag? Please advise...
    – MadyYuvi
    Apr 21, 2022 at 3:25
  • 3
    @MadyYuvi That only has blackboard bold capital letters (ABC…), not lowercase (ABC…).
    – dbmag9
    Apr 21, 2022 at 7:45
  • 3
    (For the confused, my comment above was written on my phone which autocorrected 'abc' to 'ABC' rather unhelpfully.)
    – dbmag9
    Apr 22, 2022 at 10:40
11

If you have the option to use unicode math, you can also use \Bbbi (U+1D55A) or \mitBbbi (U+02148) for the italic one (Thanks to Ingmar who pointed this out). Below you see the result in some of the commonly used fonts. If the font does not have it a question mark is shown.

many different i

2
  • 2
    Isn't it U+2148, though? And that's DOUBLE-STRUCK ITALIC SMALL I, which may or may not be what OP needs.
    – Ingmar
    Apr 21, 2022 at 5:10
  • 1
    Thanks Ingmar! I should not write answers before breakfast.
    – mickep
    Apr 21, 2022 at 5:54
6

There is Unicode character U+1D55A (MATHEMATICAL DOUBLE-STRUCK SMALL I). If you use a TeX-engine that allows you to use arbitrary fonts (like LuaLaTeX) and have a font that supports the glyph, you could use 𝕚 directly, as it were.

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