I've noticed that a lot of users (especially those asking questions) tend to use $E$ instead of $I$ for the identity matrix. Is this a common convention in certain languages?
I tried looking through the wiki pages for the identity matrix in different languages, but they all seem to use $I$ rather than $E$. I'd imagine that in German, one might use $E$ for Einheitsmatrix rather than $I$ for Identitätsmatrix, but that's just a guess.
In Russian, Identity Matrix is translated as "Edinichnaya Matritsa". "Edinichnaya" from the word "Edinitsa" what weans $1$ (one), maybe thats why in Russian it is $E$