Similar to my question here: I want to import \bigplus and \bigtimes from the mathabx package but not use the whole package as it alters the look of \int, \partial etc.
There are a lot of solutions out there for similar problems but I don't know where to start adapting them to my own needs as they seem like magic LaTeX incantations! Can anyone give me a particular solution, or help me understand how to adopt a general solution?
If possible I would like to avoid relying on the amsmath package because the journal class file I'm using does not play well with amsmath (very frustrating but I cannot do anything about this!).
Thanks!


But can you help me understand what the difference between your answers is? As far as I can see, the only differences are the slots in
– jms547 Mar 09 '21 at 18:44\DelareMathSymbol, i.e."90, "91"(Bernard) vs"A0, "A1(Steven), and the numbers in\DeclareFontShape. So what do these numbers in\DeclareFontShapemean and do?\DeclareFontShape{U}{mathx}{m}{n}{ <-6> mathx5 <6-7> mathx6 <7-8> matha7 <8-9> mathx8 <9-10> mathx9 <10-12> mathx10 <12-> mathx12 }{}? – jms547 Mar 11 '21 at 21:34