[texhax] math notation

[Philip TAYLOR]

Michael Barr wrote:
> A bit of history might help here.  In traditional typesetting, variables
> were put in italics and constants upright.  So clearly the differential d
> and the base e of the natural logarithm are constants.  

Clearly ?  "e" is most certainly a constant, but surely "i" (as in the square
root of minus one) is often referred to as an operator, and the "d" of "dx"
is (IMHO) no more similar to "e" than it is to "i" ...

** Phil.