18

My tex

\begin{equation}
 \iint \limits_{-\infty}^{+\infty} 
\end{equation}

It looks like

enter image description here

I want two limits there above and below.

How can you have two limits above and below the two integrals?

Léo Léopold Hertz 준영
  • 7,906

3 Answers3

20

You are probably expecting iterated integral, not double integral. Hence

\documentclass{article}

\begin{document} 

\newcommand{\Int}{\int\limits}

\begin{equation}
\Int_{-\infty}^{+\infty} \Int_{-\infty}^{+\infty}f(x,y) \,dx\,dy
\end{equation}

\end{document}

enter image description here

Przemysław Scherwentke
  • 37,268
11

The multiple integral macros by amsmath only support lower limits on multiple integrals.

You can get around this by using a specialized font for integrals, like the one provided by esint.

\documentclass{article}
\usepackage{amsmath}
\usepackage{esint}

\makeatletter
%% make esint definition in line with amsmath
\@for\next:={int,iint,iiint,iiiint,dotsint,oint,oiint,sqint,sqiint,
  ointctrclockwise,ointclockwise,varointclockwise,varointctrclockwise,
  fint,varoiint,landupint,landdownint}\do{%
    \expandafter\edef\csname\next\endcsname{%
      \noexpand\DOTSI
      \expandafter\noexpand\csname\next op\endcsname
      \noexpand\ilimits@
    }%
  }
\makeatother

\begin{document}

\begin{equation*}
 \iint \limits_{-\infty}^{+\infty}
\end{equation*}

\end{document}

enter image description here

egreg
  • 1,121,712
3

Here comes a possible solution

\documentclass{article}
\usepackage{amsmath}

\makeatletter
\newlength\tmp@\newlength\t@mp
\newcommand{\comp}[3]
  {\mathop{ \settowidth\tmp@{$\displaystyle\mathop{#1}^{#3}_{#2}$}
  \hbox to \tmp@{\hss \settowidth\t@mp{$\displaystyle #1$}\setlength\t@mp{.45\t@mp}
  $\displaystyle\mathop{#1}^{\hspace\t@mp #3}_{\hspace{-\t@mp}#2}$
  \hss} }}
\makeatother

\begin{document}
\[
\begin{aligned}
  &\comp{\int}{A}{B}+\int\\
  &\intop_A^B+\intop\\
  &\intop+\intop\\
  &\comp{\int}{AAA}{BBB}+\int\\
  &\intop_{AAA}^{BBB}+\int\\
  &\comp{\int}{AAAAAAAAA}{BBBBBBBBB}+\int\\
  &\intop_{AAAAAAAAA}^{BBBBBBBBB}+\int\\
\end{aligned}
%
\begin{aligned}
  &\comp{\int}{A}{B}\intop_{A}^{B}\\
  &\comp{\int}{AAA}{\rule{1cm}{10cm}}\intop_{AAA}^{\rule{1cm}{10cm}}\\
  &\comp{\int}{AAAAAAAAA}{BBBBBBBBB}\intop_{AAAAAAAAA}^{BBBBBBBBB}\\
%
  &\comp{\iint}{A}{B}\iint\limits_{A}^{B}\iint\\
  &\comp{\iint}{AAA}{BBB}\quad\iint\limits_{AAA}^{BBB}\iint
  \comp{\iint}{-\infty}{+\infty}\\
  &\comp{\iint}{AAAAAAAAA}{BBBBBBBBB}\quad\iint\limits_{AAAAAAAAA}^{BBBBBBBBB}\iint\\
%
\end{aligned}
\]
\end{document}

enter image description here enter image description hereenter image description here

Tuff Contender
  • 401
  • Welcome to TeX.SE. If you indent lines of code by four spaces -- most easily done by highlighting the rows in question and clicking o the {} "button" in the row above the edit window -- the site's software will pretty-print the code automatically. (Backticks should be used only for inline code snippets.) – Mico Dec 11 '16 at 20:52
  • I've taken the liberty of editing your code to make it minimally compilable. Providing fully compilable examples rather than code snippets that make you guess which packages might have to be loaded (here: the amsmath package for the \iint macro) can be a frustrating exercise, the more so if the reader isn't an experienced LaTeX user. – Mico Dec 11 '16 at 21:00
  • Can you please explain the purpose of \rlap? – Léo Léopold Hertz 준영 Dec 12 '16 at 08:45
  • 1
    @Masir I just use it to create the superscript +\infty. What \rlap contains is actually hidden. But I'm not sure if it works on your system since I didn't get a correct result as expected. – Tuff Contender Dec 13 '16 at 12:56