I defined a function \mathrm{fun}[a \underline{\hspace{0.5em}} \,]:=a^2, but it showed that “No Wolfram Language translation found”. Now I found that I can name a function single letter like f, g or a letter followed by a number like f1, g1. But I saw that some other people could use the function names with more than one letter. I have no idea why this issue exist. I tried to restart Mathematica but it did not work. I am doubting whether that is because of the edition of the Mathematica I use, I got the access through our university.
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