"\arctan" blocks slanted math?

[R. Lahaye]

Hi,

I have in my document as display math:

       T = arctan E

which sets the "T" as slanted (as math usually does), but the "E" after
arctan (which is a \arctan) is NOT slanted.

Is that the correct behaviour or is this a bug in LyX?
(I'm running LyX-CVS)

However, I need this "E" to be slanted in the math-way.

How can that be done?

Thanks,
Rob.