# [texhax] math notation

Michael Barr mbarr at math.mcgill.ca
Wed May 10 20:00:48 CEST 2006

"d" is an operator, but a constant operator (I never intended "constant"
to refer only to numerical constant).  As far as I am concerned i is a
number, exactly as much of a one as -1.  But all of "i", "e", "d" are
constants.  But can you imagine a variable d and \int_0^1f(d)\diff d?

Incidentally, one of my pet peeves is that the d in mit leans so far to
the right that it interferes with superscripts.  I use d^? all the time
for face operators in a simplicial object.  I suppose I could use an
upright d, but I don't in accordance with the principle enunciated in my
original post.

On Wed, 10 May 2006, Philip TAYLOR wrote:

>
>
> 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.
>