Consider:
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.
[Tex/LaTex] ‘i’ symbol in TeX
symbols
Related Solutions
I don't think it's available as a proper symbol, but you could use TikZ to draw it. By using the units em or ex, the symbol will scale corresponding to the surrounding text.
\documentclass{article}
\usepackage{tikz}
\newcommand\centerofmass{%
\tikz[radius=0.4em] {%
\fill (0,0) -- ++(0.4em,0) arc [start angle=0,end angle=90] -- ++(0,-0.8em) arc [start angle=270, end angle=180];%
\draw (0,0) circle;%
}%
}
\begin{document}
Center of Mass: \centerofmass
\Huge It scales! \centerofmass
\end{document}
Well here is one that looks kinda like cheating, it uses amsmath only, though adding calc will make the definition much simpler:
\documentclass{article}
\usepackage{amsmath}
\newlength{\crossl}
\settowidth{\crossl}{$\times$}
\newlength{\ceql}
\settowidth{\ceql}{$\times=$}
\addtolength{\ceql}{-\crossl}
\newcommand{\crosseq}{\mathrel{\makebox[\crossl][l]{$\times\hspace{-\ceql}=$}}}
\begin{document}
$f(x)\crosseq g(x)\crosseq h(x)$
\end{document}
Result:
One can also play around with the position and the symbols used:
\newcommand{\crosseq}{\mathrel{\makebox[7.7778pt][l]{$\neq$\hspace{-6.7778pt}\raisebox{-2.5pt}{$\backslash$}}}}
EDIT: Since this answer is chose I will add some more solution, this time using egreg's suggestion as poking around with boxes will likely create unexpected spacing issue:
\newcommand{\crosseq}{\mathrel{\ooalign{\hidewidth$/$\hidewidth\cr\ooalign{\hidewidth$\backslash$\hidewidth\cr$=$\cr}\cr}}}
or
\newcommand{\crosseq}{\mathrel{\ooalign{\hidewidth$/$\hidewidth\cr\ooalign{\hidewidth\raisebox{-2pt}{$\backslash$}\hidewidth\cr$=$\cr}\cr}}}
Result:
EDIT2: Add [l] option to \makebox in order to adjust alignment.
Best Answer
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.