How can I write in MathJax a circle with a bullet inside it? I know \odot, but this is a circle with a dot inside it; I want most of the circle be filled by the dark circle inside and only a thin clear rim surrounding it.
1 Answer
In Mathjax, it is hard to overlay characters and get them perfectly aligned on all screens. ($\rm\LaTeX$ has purpose-built packages.) Instead, you can use the following Unicode character (which Mathjax allows):
⦿
CIRCLED BULLET
Unicode: U+29BF, UTF-8: E2 A6 BF
$$a⦿b. ⦿^{⦿^{⦿^{⦿}}}.\Huge ⦿.$$
gives
$$a⦿b. ⦿^{⦿^{⦿^{⦿}}}.\Huge ⦿.$$
It even comes with the spacing of a binary operator,
$a⦿b$ $a{⦿}b$
$a⦿b$ $a{⦿}b$
Here's a screenshot of the above using two different renderers, HTML-CSS (with my preinstalled XITS font):
and common HTML:
If you don't want to copy-paste and have good memory, one can type \unicode{x29bf}
$\unicode{x29bf}$ for the same effect. (This works for other Unicode symbols, e.g. \unicode{x1D7D9}
$\unicode{x1D7D9}$. I am both lazy and forgetful, so I use software.)
- Some other circled Unicode symbols: $⊕⊖⊗⊘⊙⊚⊛⊜⊝⨀⨁⨂⨷⨸⦶⦷⦸⦹⦺⦻⦼⦽⦾⦿⧀⧁$.
- I couldn't find a big version to make the equivalent of
$⨀\limits_a^b$
$⨀\limits_a^b$, but Davide Cervone in the comments below has given the following beautiful suggestion (copied verbatim)
You might consider
\mathop{\vcenter{\huge ⦿}}_{n=1}^{\infty}
as more semantic and a little easier to use, plus it centers the operator, and \limits will work with that: $$\mathop{\vcenter{\huge ⦿}}_{n=1}^{\infty} abc$$ Even better might be\mathop{\vcenter{\huge\unicode[.67,.15]{x29BF}}}_{n=1}^{\infty}
, which specifies the height and depth of the character so that the limits can be better placed (though this may depend on the fonts that the viewer has installed).
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5$\begingroup$ You might consider
\mathop{\vcenter{\huge ⦿}}_{n=1}^{\infty}
as more semantic and a little easier to use, plus it centers the operator, and\limits
will work with that: $$\mathop{\vcenter{\huge ⦿}}_{n=1}^{\infty} abc$$ Even better might be\mathop{\vcenter{\huge\unicode[.67,.15]{x29BF}}}_{n=1}^{\infty}
, which specifies the height and depth of the character so that the limits can be better placed (though this may depend on the fonts that the viewer has installed). $\endgroup$ Feb 10, 2022 at 18:07 -
$\begingroup$ @DavideCervone thank you $\vcenter{\stackrel{⦿{\tiny \triangle} ⦿}{\smile}}$ I have added this verbatim to the answer. $\endgroup$ Feb 11, 2022 at 12:59
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1
$\bigodot\kern-0.835em\bullet$
looks okay to me... $\endgroup$$\require{enclose}\enclose{circle}{\bullet}$
$\require{enclose}\enclose{circle}{\bullet}$ doesn't look great (which I found from here $\endgroup$