Take the 2-minute tour ×
TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. It's 100% free, no registration required.

how can I avoid that the following expression

\documentclass[a4paper,fontsize=14pt]{scrbook}  
\usepackage{mathtools}
\usepackage{lmodern}
\begin{document}
\begin{align}
    a = \sqrt[m]{\sum_{i=1}^{n}b_{i}^m}.
\end{align}
\end{document}

is displayed in this form ($m$ is cut by the root symbol):

enter image description here

Thanks for you help.

share|improve this question
    
Try to use \sqrt[m\,]{\sum...}. –  wipet Jun 24 at 10:59
1  
please make a complete document that produces that display and post, the input shown would set the summation in inline style not with the limits above and below. –  David Carlisle Jun 24 at 10:59
    
That is not possible with standard LaTeX math mode. So do what David said! –  Herbert Jun 24 at 11:02
    
Sorry for not posting the full code. Now I think, the problem might be the lmodern package in combination with the 14pt fontsize. –  Ankaios Argo Jun 24 at 11:13
    
And the m\, does help! –  Ankaios Argo Jun 24 at 11:14

2 Answers 2

up vote 7 down vote accepted

It's the usual problem due to the setting of the math extension font done by lmodern.sty, which defines OMX/lmex/m/n for it with this completely wrong font definition file:

\ProvidesFile{omxlmex.fd}[2009/10/30 v1.6 Font defs for Latin Modern]

\DeclareFontFamily{OMX}{lmex}{}
\DeclareFontShape{OMX}{lmex}{m}{n}{%
   <->sfixed*lmex10%
   }{}
\endinput

This means that lmex10 is used no matter what the surrounding font size is. This might seem to work at standard sizes (it doesn't, however, try with \sum in a subscript).

I usually suggest to reinstate the Computer Modern math extension font, but applying the fact that nowadays arbitrary scaling is possible.

\documentclass[a4paper,fontsize=14pt]{scrbook}
\usepackage{mathtools}
\usepackage{lmodern}

\DeclareFontShape{OMX}{cmex}{m}{n}{%
  <-7.5>cmex7
  <7.5-8.5>cmex8
  <8.5-9.5>cmex9
  <9.5->cmex10
}{}
\DeclareSymbolFont{largesymbols}{OMX}{cmex}{m}{n}


\begin{document}
\[
a = \sqrt[m]{\sum_{i=1}^{n}b_{i}^m}.
\]
\end{document}

enter image description here

share|improve this answer
    
Thanks, that solves the problem! If you have some additinal time, would be nice, if you could explain, how you came up with the numbers. –  Ankaios Argo Jun 24 at 12:56
    
@AnkaiosArgo The figures in the \DeclareFontShape command are based on the available optical sizes for cmex; if the requested size is around 7pt (or below, for second level sub/superscripts), use cmex7; if it is around 8pt, use cmex8 and so on; cmex10 is the largest size available, so from 9.5pt up there's no other choice. –  egreg Jun 24 at 13:00

Something strange in the lmodern font metrics it appears.

You can shift the index with \leftroot

\documentclass[a4paper,fontsize=14pt]{scrbook}  
\usepackage{mathtools}
\usepackage{lmodern}
\begin{document}
\begin{align}
    a = \sqrt[\leftroot{2}m]{\sum_{i=1}^{n}b_{i}^m}.
\end{align}
\end{document}

enter image description here


Original computer modern answer:

The input you show would use an inline style unlike the image shown, and display style should not over print the index Please always post a complete document that shows the problem:

enter image description here

\documentclass{article}

\usepackage{amsmath}

\begin{document}

$a = \sqrt[m]{\sum_{i=1}^{n}b_{i}^m}$

\[
a = \sqrt[m]{\sum_{i=1}^{n}b_{i}^m}
\]

\end{document}
share|improve this answer
    
Thanks a lot David! The leftroot is a nice workaround. However, it seems to be better to solve the problem at the "root". Thus I think egreg's solutions is the way to go. –  Ankaios Argo Jun 24 at 12:54
    
@AnkaiosArgo you made an old man very happy: chat.stackexchange.com/transcript/message/16249651#16249651 –  David Carlisle Jun 24 at 12:56

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.