I am trying to get a sans math version of the lmodern family using \DeclareMathVersion
but my approach does not work and I do not see why. But I have to admit that I am not sure whether I use the correct fonts:
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\DeclareMathVersion{sansmath}
% Math letters from Latin Modern Sans
\SetSymbolFont{letters}{sansmath}{OML}{lmsso}{m}{it}
% Math operators
\SetSymbolFont{operators}{sansmath}{OT1}{lmss}{m}{n}
% Math symbols
\SetSymbolFont{symbols}{sansmath}{OMS}{lmsy}{m}{n}
% Large symbols
%\SetSymbolFont{largesymbols}{sansmath}{OMX}{lmssex}{m}{n}
\begin{document}
\mathversion{normal}
$a b c \alpha \beta$
\mathversion{sansmath}
$a b c \alpha \beta$
\end{document}
In both cases the result is the normal serif math font.