# Change font size globally. With KOMA-Script: bad size for indexes and exponents

I need to change the font-size of my document. So far, I use KOMA-Script in order to do this.

I noticed that the appearance of the same mathematical text is not the same with different font sizes. I think it is a bug of KOMA-Script. Do you know another way to change the font size globally? Or, can this bug of KOMA-Script be fixed?

Thanks

# MWE

\documentclass{scrreprt}
\usepackage{amsmath}
\KOMAoptions{fontsize=50pt}

\begin{document}
50pt\\
$\sqrt{\displaystyle \int_0^1 f(t) dt + \displaystyle \int_0^1 f(t) dt}$

\end{document}


and

\documentclass{scrreprt}
\usepackage{amsmath}
\KOMAoptions{fontsize=10pt}

\begin{document}
10pt\\
$\sqrt{\displaystyle \int_0^1 f(t) dt + \displaystyle \int_0^1 f(t) dt}$

\end{document}


I noticed that the appearance of the same mathematical text is not the same with different font sizes. I think it is a bug

this is expected behaviour rather than a bug, latex does scream at you

LaTeX Font Warning: Font shape OMX/cmex/m/n' in size <50> not available
(Font)              size <24.88> substituted on input line 7.


because by default it is set up assuming that computer modern is only available in a fixed set of sizes.

Normally

\RequirePackage{fix-cm}


is all you need but here you get

LaTeX Font Warning: Font shape OMX/cmex/m/n' in size <50> not available
(Font)              size <24.88> substituted on input line 8.


so one extra setting needed:

\RequirePackage{fix-cm}
\documentclass{scrreprt}
\usepackage{amsmath}
\KOMAoptions{fontsize=50pt}
\DeclareFontShape{OMX}{cmex}{m}{n}{%
<-> cmex10%
}{}
\begin{document}
50pt\\
$\sqrt{\displaystyle \int_0^1 f(t) dt + \displaystyle \int_0^1 f(t) dt}$

\end{document}


Note that depending on the reason for wanting a large font it is often preferable to use a more standard design size but then just scale the output, so for example get latex to set a 10pt document on a paper size 1/5 of the desired output then scale the pdf by 5. It depends a bit if the intention is for large print to be read close (for those with impaired vision) or if it is to be read as a normal document from a long way off as in a projected display, where you want to scale the page not the fonts.