[Tex/LaTex] LaTeX command for double lower index summation

Question

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Separate long math text under sum symbol into different lines?

(3 answers)

Closed 8 years ago.

I would like to know what is the latex command to include a double lower index using sigma notation (i.e: second index lies underneath the first index)?

I tried typing:

\displaystyle\sum_{m,n=-\infty, \; (m,n)\neq (0,0)}^{\infty}
\left[
  \frac{1}{(z-2 m\omega_{1} - 2 n\omega_{2})^{2}}
 -\frac{1}{   4(m\omega_{1} +   n\omega_{2})^{2}}
\right] 

I would appreciate the assistance. Thanks

Answer 1

The \substack command from the amsmath package can do what you are after:

\documentclass{article}

\usepackage{amsmath}

\begin{document}
\begin{equation*}
  \sum_{\substack{m,n=-\infty,\\(m,n)\neq (0,0)}}^{\infty}\left[\frac{1}{(z-2 m\omega_{1}-2 n\omega_{2})^{2}}-\frac{1}{4(m\omega_{1}+n\omega_{2})^{2}}\right]
\end{equation*}
\end{document}

Or without the comma, since the next condition is on a new line:

\documentclass{article}

\usepackage{amsmath}

\begin{document}
\begin{equation*}
  \sum_{\substack{m,n=-\infty\\(m,n)\neq (0,0)}}^{\infty}\left[\frac{1}{(z-2 m\omega_{1}-2 n\omega_{2})^{2}}-\frac{1}{4(m\omega_{1}+n\omega_{2})^{2}}\right]
\end{equation*}
\end{document}