# how to scale math font only

I am trying to mimic our institute's PPt-template for presentation foils using the beamer-class. The corporate quidelines prescribe the use of Helvetica as the main font. However, package helvet does not provide a good mathematical font. Therefore I want to replace it with the math font from the cmbright package:

\documentclass{beamer}

\usepackage{lmodern}
\usepackage[T1]{fontenc}

%main font Helevtica
\renewcommand{\familydefault}{\sfdefault}
\usepackage{helvet}

%prevent beamer from meddling with math fonts
\usefonttheme{professionalfonts}

%following lines borrowed from cmbright.sty
\DeclareSymbolFont      {operators} {OT1}{cmbr}{m}{n}
\DeclareSymbolFont        {letters} {OML}{cmbrm}{m}{it}
\SetSymbolFont      {letters}{bold} {OML}{cmbrm}{b}{it}
\DeclareSymbolFont        {symbols} {OMS}{cmbrs}{m}{n}
\DeclareMathAlphabet{\mathit} {OT1}{cmbr}{m}{sl}
\DeclareMathAlphabet{\mathbf} {OT1}{cmbr}{bx}{n}
\DeclareMathAlphabet{\mathtt} {OT1}{cmtl}{m}{n}
\DeclareMathAlphabet{\mathbold}{OML}{cmbrm}{b}{it}
\DeclareMathSymbol{\alpha}{\mathalpha}{letters}{11}
\DeclareMathSymbol{\beta}{\mathalpha}{letters}{12}
\DeclareMathSymbol{\gamma}{\mathalpha}{letters}{13}
\DeclareMathSymbol{\delta}{\mathalpha}{letters}{14}
\DeclareMathSymbol{\epsilon}{\mathalpha}{letters}{15}
\DeclareMathSymbol{\zeta}{\mathalpha}{letters}{16}
\DeclareMathSymbol{\eta}{\mathalpha}{letters}{17}
\DeclareMathSymbol{\theta}{\mathalpha}{letters}{18}
\DeclareMathSymbol{\iota}{\mathalpha}{letters}{19}
\DeclareMathSymbol{\kappa}{\mathalpha}{letters}{20}
\DeclareMathSymbol{\lambda}{\mathalpha}{letters}{21}
\DeclareMathSymbol{\mu}{\mathalpha}{letters}{22}
\DeclareMathSymbol{\nu}{\mathalpha}{letters}{23}
\DeclareMathSymbol{\xi}{\mathalpha}{letters}{24}
\DeclareMathSymbol{\pi}{\mathalpha}{letters}{25}
\DeclareMathSymbol{\rho}{\mathalpha}{letters}{26}
\DeclareMathSymbol{\sigma}{\mathalpha}{letters}{27}
\DeclareMathSymbol{\tau}{\mathalpha}{letters}{28}
\DeclareMathSymbol{\upsilon}{\mathalpha}{letters}{29}
\DeclareMathSymbol{\phi}{\mathalpha}{letters}{30}
\DeclareMathSymbol{\chi}{\mathalpha}{letters}{31}
\DeclareMathSymbol{\psi}{\mathalpha}{letters}{32}
\DeclareMathSymbol{\omega}{\mathalpha}{letters}{33}
\DeclareMathSymbol{\varepsilon}{\mathalpha}{letters}{34}
\DeclareMathSymbol{\vartheta}{\mathalpha}{letters}{35}
\DeclareMathSymbol{\varpi}{\mathalpha}{letters}{36}
\DeclareMathSymbol{\varrho}{\mathalpha}{letters}{37}
\DeclareMathSymbol{\varsigma}{\mathalpha}{letters}{38}
\DeclareMathSymbol{\varphi}{\mathalpha}{letters}{39}
\let\upDelta\Delta
\let\upOmega\Omega
\let\upGamma\Gamma
\let\upTheta\Theta
\let\upLambda\Lambda
\let\upXi\Xi
\let\upPi\Pi
\let\upSigma\Sigma
\let\upUpsilon\Upsilon
\let\upPhi\Phi
\let\upPsi\Psi

%doesn't seem to have an effect
%\DeclareMathSizes{12}{12.5}{10}{10}

\begin{document}
\begin{frame}
Some Math E$E$
\end{frame}
\end{document}

This works quite well, except that the math letters are somewhat smaller than the normal Helvetica text. Is there a way to scale the fontsize, say by 1.1, if the typesetter is in math mode?

You can try,

\DeclareMathSizes{10}{10.5}{7}{7}

the format of the command is:

\DeclareMathSizes {t-size} {mt-size} {s-size} {ss-size}

Basically, we instruct the use of a <mt-size> as the math text size, <s-size> as the script size and <ss-size> the scriptscript size to be used in math, when <t-size> is the current text size. You can adjust the parameters to suit. You can also find more information at http://tex.loria.fr/general/new/fntguide.html

You can also scale down the helvetica font if you wish

\usepackage[scaled=0.95]{helvet}

This is probably a better solution than scaling up the maths fonts.

When using the \DeclareMathSizes the first parameter for the text font must be exactly what is used in the class declaration. For example with Beamer rather declare \documentclass[10pt]{beamer}, otherwise the command will appear as it is not working. It is also normal when you declare math sizes to provide a range of math font sizes for all the text fonts:

\DeclareMathSizes{9.8}{17}{7}{7}
\DeclareMathSizes{10.0}{17}{7}{7}
\DeclareMathSizes{10.95}{10}{7}{7}   % For size 10 text
\DeclareMathSizes{11}{19}{13}{9}      % For size 11 text
\DeclareMathSizes{12}{20}{14}{10}     % For size 12 text

You can test the above with the minimal example below, which is somewhat reduced from that originally posted:

\documentclass[10pt]{beamer}

\usepackage{lmodern}
\usepackage[T1]{fontenc}

%main font Helevtica
\renewcommand{\familydefault}{\sfdefault}
\usepackage{helvet}

%prevent beamer from meddling with math fonts
\usefonttheme{professionalfonts}

%following lines borrowed from cmbright.sty
\DeclareSymbolFont      {operators} {OT1}{cmbr}{m}{n}
\DeclareSymbolFont        {letters} {OML}{cmbrm}{m}{it}
\SetSymbolFont      {letters}{bold} {OML}{cmbrm}{b}{it}
\DeclareSymbolFont        {symbols} {OMS}{cmbrs}{m}{n}
\DeclareMathAlphabet{\mathit} {OT1}{cmbr}{m}{sl}
\DeclareMathAlphabet{\mathbf} {OT1}{cmbr}{bx}{n}
\DeclareMathAlphabet{\mathtt} {OT1}{cmtl}{m}{n}
\DeclareMathAlphabet{\mathbold}{OML}{cmbrm}{b}{it}
\DeclareMathSymbol{\alpha}{\mathalpha}{letters}{11}
\DeclareMathSymbol{\beta}{\mathalpha}{letters}{12}
\DeclareMathSymbol{\gamma}{\mathalpha}{letters}{13}
\DeclareMathSymbol{\delta}{\mathalpha}{letters}{14}
\DeclareMathSymbol{\epsilon}{\mathalpha}{letters}{15}

\DeclareMathSizes{9.8}{17}{7}{7}
\DeclareMathSizes{10.0}{17}{7}{7}
\DeclareMathSizes{10.95}{10}{7}{7}   % For size 10 text
\DeclareMathSizes{11}{19}{13}{9}      % For size 11 text
\DeclareMathSizes{12}{20}{14}{10}     % For size 12 text

\begin{document}
\begin{frame}
This is a test $a^{2}+\gamma\sigma^{\epsilon}$

\fontsize{9.8pt}{13pt}\selectfont
This is a test $a^{2}+\gamma\sigma^{\epsilon}$

%\fontsize{10pt}{13pt}\selectfont
This is a test $a^{2}+\gamma\sigma^{\epsilon}$
\end{frame}
\end{document}
• @Yannis: I edited the example to make it a working minimal one. The \DeclareMathSizes doesn't seem to have an effect, but \usepackage[scaled=0.95]{helvet} works fine! Thanks a lot! (+1). Jan 7 '11 at 13:26
• I wish I could edit my own comment. Sorry for misspelling your name. Jan 7 '11 at 13:39
• @Alexander Please see my edit. Not to worry about the name, you can find it spelt both ways! \textgreek{Giannis} with babel greek option! Jan 7 '11 at 16:17
• @YiannisLazarides It would be really great if you could explain, why 10.95 works for size 10 text, please
– TimK
Mar 17 '19 at 10:24
• I didn't manage to make DeclareMathSizes working for Memoir Class and 14pt, do you know if there is anything that specify it doesn't work?
– JKHA
Jul 11 '19 at 11:34