Writing an alpha integral

Question

How can I change this integral $$\oint_V f(s) \,ds$$ to display alpha instead of o?

I tried to write alpha instead of o, but it did not work.

Answer 1

This is more or less taken from this answer. All I did was to change R to \alpha and adjust the kerning.

\documentclass[fleqn]{article}
\usepackage{mathtools}
\newcommand{\alphaint}{\mathop{\mathrlap{\pushalpha}}\!\int}
\newcommand{\pushalpha}{\mathchoice
  {\mkern4mu \alpha}
  {\mkern2mu\scriptstyle \alpha}
  {\mkern1.5mu\scriptscriptstyle \alpha}
  {\mkern1mu\scriptscriptstyle \alpha}
}
\begin{document}
\[
\left|\alphaint_a^b f\right|\textstyle\left|\alphaint_a^b f\right|_{\left|\alphaint_a^b f\right|}
\]
\[\alphaint\limits_a^b f(s)\,\mathrm{d}s\]

\end{document}

What might be more useful than this particular adaptation could be the way to find related posts: all I did was to do a Google picture search for site:tex.stackexchange.com oint customize and once the pic with the R in the integral shows up one can guess that it should be possible to replace the R by whatever. The danger, though, of this approach is that we keep on copying existing solutions and decrease the chances of having independent takes on problems. Yet at least I link to the more original post.

Answer 2

Into your document I have seen only the symbol \int over \alpha only into a formula. Here there is my minimal proposal. It is works :-). If \alpha seems too big for you, you can precede the command \scriptstyle or \scriptscriptstyle style before of \alpha: for example

\newcommand{\intalpha}{\makebox[0pt][c]{$\displaystyle\int$}\mkern-5mu\scriptstyle\alpha\,}

to obtain a small o smaller \alpha symbol.

\documentclass[a4paper,12pt]{article}
\newcommand{\intalpha}{\makebox[0pt][c]{$\displaystyle\int$}\mkern-5mu\alpha\,}
\newcommand{\intalphae}{\makebox[0pt][c]{$\displaystyle\int_a^b$}\mkern-8mu\alpha\,}

\begin{document}
\[\intalpha f(t)dt=\frac{e_0 ba}{\alpha}\]
\[\intalphae f(t)dt=\frac{e_0 ba}{\alpha}\]

\end{document}