Math & Science ⇒ Double Sum with additional Condition

[pajacek]

Hey, I have no idea how to type something like that

Code: Select all

\displaystyle\sum^k_{i=1}\displaystyle\\sum^k_{\substack{j=1 \\ i<j}}q_i q_j

but with additional condition i<j under/between both sum symbols to get it finer.

[localghost]

Try something like this.

Code: Select all

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}

\begin{document}
  \[
    \underset{i<j}{\sum^k_{i=1}\sum^k_{j=1}}\,q_i q_j
  \]
\end{document}

Best regards and welcome to the board
Thorsten

[pajacek]

Great, this is exactly I need! Thank you for your help and welcome.