I am aware of \oint. I want the circle to have a counterclockwise arrow on it, as is sometimes seen in complex analysis.
[Tex/LaTex] Integral with a circle and an arrow indicating clockwise or counter clockwise
math-mode
Related Solutions
To answer your question: there is no single answer. Even at our Mathematics department, for the first grade students, there are two professors of linear algebra, one uses $\bm{v}$ (bold math from bm package), the other one uses $\vec{v}$.
I would not use bar for complex numbers, because $\bar{z}$ often denotes the conjugate of $z$. I think that you should always make clear in the text whether you are real or complex.
Generally: In my opinion, you can use whichever notation you want, as far as you use it consistently in the whole work, and make clear (in Table of Notations in the Preface, or in the Introduction) what notation you use.
Two examples with txfonts and esint, both provide the \ointctrclockwise macro, but look different. There is \ointclockwise as well.
\documentclass{article}
\usepackage{txfonts}
\begin{document}
$\ointctrclockwise\limits_{\Gamma} x \mathrm{d}\gamma$
\end{document}
esint version:
\documentclass{article}
\usepackage{esint}
\begin{document}
\[\ointctrclockwise\limits_{\Gamma} x \mathrm{d}\gamma\]
\end{document}
Best Answer
According to the symbols document (
texdoc symbolson a TeX Live system), you can use theesintpackage. Thetxfontsalso have them but they have other problems.MnSymbolalso have them but does not suit most fonts.