Thanks in advance.
As far as I know, it's just a plain capital O. If you mean something
else, try DeTeXify:
http://detexify.kirelabs.org/classify.html
Draw the symbol and look at the suggestions.
--
Arturo Magidin
yeah, it's like O but opened to the top left (just like you wrote italic
O with a pen!), DeTeXify says it's \mathcal{O}
but when I compile text it looks yet differently to what DeTeXify and
other sites show ...
Hi!
Try $\mathcal{O}$
HTH
Jose L.
Ups. You need load amssymb package.
Sorry!
Jose L.