make summation sign big without affecting the size of lower bound of summation

Question

This is a follow up question related to this post making a big summation sign

I am trying to rescale the sum sign in the same way as in the above post. The problem is that the lower bound of the sum also becomes bigger which I don't want.

 \documentclass[11pt,a4paper,oneside]{report} 
 \usepackage[pdftex]{graphicx} 
 \usepackage[T1]{fontenc} 
 \usepackage{fouriernc}
 \usepackage{mathtools}
 \usepackage{amsfonts,amsmath,amssymb,amsthm} 
 \usepackage[a4paper, hmargin={3.5cm,3cm}, vmargin={2.5cm,2.5cm}]{geometry} 
 \usepackage{relsize}

 \begin{document}

 \begin{equation}
 c_{ij}=\sum_{i^{\prime}<i^{''},j^{\prime}<j^{''}}\begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \end{equation}

 \begin{equation}
 c_{ij}=\mathlarger{\mathlarger{\sum}}_{i^{\prime}<i^{''},j^{\prime}<j^{''}}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \end{equation}

 \begin{equation}
 c_{ij}=\mathlarger{\mathlarger{\mathlarger{\sum}}}_{i^{\prime} <i^{''},j^{\prime}<j^{''}}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \end{equation}

 \end{document}

output

I think the second version looks best, unfortunately the lower bound is clearly enlarged as well. What can be done to prevent it? Also, why the delimiters of the matrices are not adjusted to the content they surround? Thank you.

Answer 1

I see no reason for making the summation symbol larger. Big matrices are no excuse.

If you really want to ignore this advice, here's the correct way to proceed with \mathlarger:

\documentclass[11pt,a4paper,oneside]{report}
\usepackage{fouriernc}
\usepackage{mathtools}
\usepackage{relsize}

\begin{document}

\begin{equation}
c_{ij}=\sum_{i'<i'',\,j'<j''}
\begin{pmatrix}
i&i'&i''\\1&2&3
\end{pmatrix}
\end{equation}

\begin{equation}
c_{ij}=\mathop{\mathlarger{\sum}}_{i'<i'',\,j'<j''}
\begin{pmatrix}
i&i'&i''\\1&2&3
\end{pmatrix}
\end{equation}

\begin{equation}
c_{ij}=\mathop{\mathlarger{\mathlarger{\sum}}}_{i'<i'',\,j'<j''}
\begin{pmatrix}
i&i'&i''\\1&2&3
\end{pmatrix}
\end{equation}

\end{document}

I avoided the triple \mathlarger as it's incredibly awful and I've no doubt that the top one is right.

Note that i' is equivalent to i^{\prime}; for a double prime either use

i^{\prime\prime}

or the simpler

i''

but never i^{''}. Also a thin space \, after the comma in the summation limit is better.

Answer 2

One should always listen to egreg with his math and tex advices! However, if circumstances are severe, here is another way:

 \documentclass[11pt,a4paper,oneside]{report}
 \usepackagegraphicx}
 \usepackage[T1]{fontenc}
 \usepackage{fouriernc}
 \usepackage{mathtools}
 \usepackage{amsfonts,amssymb,amsthm}
 \usepackage[a4paper, hmargin={3.5cm,3cm}, vmargin={2.5cm,2.5cm}]{geometry}
 \usepackage{relsize}

 \DeclareMathOperator*{\Sum}{\mathlarger{\mathlarger{\sum}}}
 \DeclareMathOperator*{\SSum}{\mathlarger{\mathlarger{\mathlarger{\sum}}}}

 \begin{document}

 \begin{equation}
 c_{ij}=\sum_{i^{\prime}<i^{''},j^{\prime}<j^{''}}\begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \end{equation}

 \begin{equation}
 c_{ij}=\Sum_{i^{\prime}<i^{''},j^{\prime}<j^{''}}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \end{equation}

 \begin{equation}
 c_{ij}=\SSum_{i^{\prime} <i^{''},j^{\prime}<j^{''}}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \begin{pmatrix*}[c]
 i&i^{\prime}&i^{''}\\1&2&3
 \end{pmatrix*}
 \end{equation}

 \end{document}