# font size in math mode

$\sum\limits_{\substack{locations \\ L_j}}$

The word locations is quite long - longer than the summation symbol Sigma.

I would like to control the size of only the word locations, but I am having trouble

1. $\sum\limits_{\substack{ locations \\ L_j}}$ has no effect on the size of locations.

2. \fontsize{0.5cm}{1pt}\selectfont $\sum\limits_{\substack{locations \\ L_j}}$ makes the summation symbol sigma smaller but not *locations

3. inserting \tiny, \scriptsize etc has no discernable affect. Nor does \text{\tiny locations}, etc.

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Using \text{\tiny{locations}} does make it a bit smaller. To make it really small, you could try \scalebox.

\documentclass[10pt,a4paper]{article}
\usepackage{amsmath}
\usepackage{graphicx}
\begin{document}
$\sum\limits_{\substack{\scalebox{0.5}{locations} \\ L_j}}$

$\sum\limits_{\substack{\text{\tiny{locations}} \\ L_j}}$

$\sum\limits_{\substack{\text{locations} \\ L_j}}$
\end{document}

Another option would be to use \mathclap from the mathtools package to horizontally smash locations. This allows the summand to appear on top of locations (so you don't get a big space after the sum.

\documentclass[10pt,a4paper]{article}
\usepackage{mathtools}
\begin{document}
$\sum\limits_{\substack{\mathclap{\text{locations}} \\ L_j}}$ A
\end{document}

However, I think the best option would be to define some notation to avoid this construction.

Let $\Lambda$ represent the set of all locations...

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looks better! although i do prefer your "Let $\Lambda$ ..." formulation, i think the others would look better with just a tiny bit of extra space between the two lines. maybe \\[.2ex]; a \mathstrut is probably too much, but the lack of descenders on locations is allowing too much "compaction". – barbara beeton Apr 7 '14 at 14:12
As a mathematician, I am totally on board with the notation-solution. But when you give a presentation to a non-mathematics audience, you try to be as light on notation as possible - using English words rather than letters. Hence my problem here. Thank you, though, it is a good point. – cmo Apr 9 '14 at 0:08

Good morning,

I suggest :

\sum\limits_{\substack{ {\scriptscriptstyle \text{locations}} \\ L_j}}{y}

In a more general manner, in math mode you can use \displaystyle ; \textstyle ; \scriptstyle and \scriptscriptstyle to control font size.

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You can use \mbox:

$\sum\limits_{\substack{\mbox{\tiny {\emph{locations}}}\\ L_j}}$

Remove \emph if you do now want the text to be slanted.

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What is the difference between \mbox{} and \text{}? The OP had tried the second one. – Sigur Apr 7 '14 at 14:20
\mbox uses the current text font. The size is constant and does not change in subscripts, superscripts, fractions,etc. \text of package amstext (or amsmath) uses the current text font, but adapt the size according to the current math style. Therefore it needs \mathchoice that has an efficiency impact that the text is set four times for all math styles and later, when TeX knows the math style, it chooses the right version. For more boxes see for example link – Tahtisilma Apr 7 '14 at 14:42

One easy way I found to make math font smaller is to wrap a "_{ }" around your math/text - effectively making it a subscript of an invisible character.

$\sum\limits_{ \substack{ _{locations} \\ L_j} }$