Angularjs controller communicate with another controller in a different file

Angularjs controller communicate with another controller in a different file

I have one controller in file a, and when it does something I want it to
call a function, or a controller in file b. Is that possible? I'm using
ng-grid, so my reasoning for this is when afterSelectionChange is called
in file a, I want my other grid to update, and I can't merge the files or
use a $watch function since that takes up too much time when loading a
page. I am ultimately trying to fix this problem too. They are the same:
Ng-Grid flickers grid when updating
and this is just another look at it. If someone could answer either that
would be great!