I searched several times in vain to solve this problem. After finding a solution, I thought i’d put it up here.
The problem
Formatting of units using siunitx in LaTeX does not match the typeface of the body text.
We like to use the helvet package to get a close approximation to Helvetica in LaTeX. With the formatting of SI units taken care of with the package siunitx, the units themselves were in a sans serif typeface (sf-default) but not in Helvetica.
The solution
It was hiding in the documentation (of course)! Add the option to set detect-all to true.
\RequirePackage[detect-all=true]{siunitx}
This line can be added to the preamble or to the .cls file as I’ve done here.
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This post is part of a series of tips.