Changing Font _Without_ Changing Weight (Bold)

Question

I feel like this question has probably already been asked, but I cannot find it...

I am using the default article class. I want to create a macro \ab which does the following: it simply prints "ab" in upright, Roman font in math mode. However, I want to be able to use this in settings where the current font is Sans Serif (\sffamily) and/or where the font is bold (using \bfseries \boldmath).

Just writing \newcommand{\ab}{\textup{ab}} does almost all of this: the only issue is that it obviously doesn't do anything with the font; so it's sometimes Sans Serif. I don't know how to change the font other than \normalfont or \textnormal, but these both destroy any bold information. So if I do \newcommand{\ab}{\textnormal{ab}} then I never get bold.

Any help would be most appreciated!

Answer 1

\mathrm{ab} will give the math Roman font (and math Roman bold font in \boldmath) note that isn't by default Times Roman, but you can chose a Times Roman clone style for your document with for example \usepackage{newtxtext,newtxmath}