I would like to write something above equation sign. One may do it with \stack{#1}{#2} command and it works fine if #1 and #2 are the same length, example:
$\stackrel{(3)}{=}$
will result in

But if I would like to have longer text above =, for example:
$\stackrel{x_1 \neq x_2}{=}$
then I will get

which is not what I want.
I want the "=" to adjust it's size to the thing that's written above, so something like

Is there a command which will do it automaticaly? Or if not - how can i do it manually?
Thanks for quick response :)
– pbialy May 13 '14 at 14:41