[texhax] derivatives and integrals: math operators

[Natércia Fernandes]

Hi all.

Sorry for not having thanked earlier who answered my question, but I was away 
and read the answers only now.

When I put this question, I didn't mean to start any "war".  I just wanted to 
be clarified whether it's more correct to use italic or upright "d" for 
derivatives and integrals, since I do use them a lot and I do want to follow 
the most appropriate notation.
I see the opinions are divided.  The mathematician Phil Parker defended 
strongly the italic "d" as I have seen it elsewhere. The oher participants 
that took a position defended the upright "d" (independently of being or not 
mathematicians). It seems there isn't a rule (at least a pacifically followed 
by everyone).

As a side product, I got another doubt: the derivatives and integrals are or 
are not mathical operators? I thought they were, but Phil Parker said neither 
of them was. However, Xavier Sabate also classified them as important operators 
and others also referred to them as operators...

Once again, thanks to everyone who answered.
Natércia