Integral Sign $\int...$ [duplicate]

Question

does anybody know how to write integral signs in LaTex that are slanted to the left, and not the right. See here if you do not know what I mean:

(From http://en.wikipedia.org/wiki/File:Integral_Uprightness.svg)

This is how it is written in Bulgaria and Russia and many other places so I am curious. Thank you.

My problem is that the integral sign now is

$$
\int ...
$$

and is leaning to the right, not the left like shown in the picture I attached. I want to know how to write it so that it is slanted to the left. Thank you

Answer 1

This answer follows the additional Russian typographic tradition (Figure 5 of http://www.staff.uni-giessen.de/partosch/eurotex99/zaitsev.pdf) of having the limits above and below the integral sign in \displaystyle. The \rint is essentially an \int (of the current math style) with a 15 degree rotation applied to it.

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator*{\rint}{\ThisStyle{\rotatebox{15}{$\SavedStyle\!\int\!$}}}
\usepackage{scalerel}
\usepackage{graphicx}
\parskip 1ex
\begin{document}
\[ 
f=\int_0^t A d\tau =\rint_0^t A d\tau
\]
\centering
\(
f=\int_0^t A d\tau =\rint_0^t A d\tau
\)\par
\(
\scriptstyle f=\int A d\tau =\rint A d\tau
\)\par
\(
\scriptscriptstyle f=\int A d\tau =\rint A d\tau
\)
\end{document}

---

And here is a slight variation on the above solution in which a 30% horizontal stretch is applied to the integral sign, in an attempt to provide a width that is more in line with the literature.

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator*{\rint}{\ThisStyle{\hstretch{1.3}{\rotatebox{18}{$\SavedStyle\!\int\!$}}}}
\usepackage{scalerel}
\usepackage{graphicx}
\parskip 1ex
\begin{document}
\[ 
f=\int_0^t A d\tau =\rint_0^t A d\tau
\]
\centering
\(
f=\int_0^t A d\tau =\rint_0^t A d\tau
\)\par
\(
\scriptstyle f=\int A d\tau =\rint A d\tau
\)\par
\(
\scriptscriptstyle f=\int A d\tau =\rint A d\tau
\)
\end{document}

---

And here is a final variation of the 1st solution in which the \rint sign is always a scaled version of the \textstyle\rint, the net effect being to make a particularly wider symbol in \displaystyle than either of the two other approaches.

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator*{\rint}{\scalerel*{\rotatebox{17}{$\!\int\!$}}{\int}}
\usepackage{scalerel}
\usepackage{graphicx}
\parskip 1ex
\begin{document}
\[ 
f=\int_0^t A d\tau =\rint_0^t A d\tau
\]
\centering
\(
f=\int_0^t A d\tau =\rint_0^t A d\tau
\)\par
\(
\scriptstyle f=\int A d\tau =\rint A d\tau
\)\par
\(
\scriptscriptstyle f=\int A d\tau =\rint A d\tau
\)
\end{document}