Mathrax Sudoku (Daily Sudoku League #81)

I wanted to post this Mathrax Sudoku in my previous post in The League of Extraordinary Ladies and Gentlemen, but during testing, this puzzle was found broken, so I posted Jigsaw XV Sudoku in the previous post. I have fixed this puzzle and did the self-testing on this to find that this puzzle is quite good now and has a very logical solving path and uses almost all the Math and Even/Odd hints are given in this puzzle. Hopefully, this puzzle will be good practice for 1st Round of the Sudoku Grand Prix Championship 2015 for the readers of this blog who has yet to participate in this championship. With this Submission now one can find all the Sudoku variations appearing in this round on this website. All these variations are mentioned below
Odd Sudoku,
Renban Sudoku,
Thermometer Sudoku,
Arrow Sudoku,
Next to Nine Sudoku,
All Odd/Even Sudoku,
Round Off Sudoku and
Jigsaw XV Sudoku

This Mathrax Sudoku is my 81st contribution to The League of Extraordinary Ladies and Gentlemen. Can you solve this Mathrax Sudoku puzzle?

Rules of Mathrax Sudoku

Classic Sudoku Rules apply. Additionally, some intersections of the grid lines are marked by a number and an operator in a circle or a letter in a circle. A number clue is the value of the operation applied to both pairs of diagonally opposite cells. An ‘O‘ indicates all four surrounding digits are odd; an ‘E‘ indicates all four surrounding digits are even.