How to make equation in matlab algorithm?

How do I transform this equation into matlab algoritm?

eqn: where M and N are the dimensions of the image, and X is the intensity of the pixel located at row i and column j in the image map.

Answer 1

[Jan]

E = sum(X(:)) / numel(X);

or

E = mean(X(:))

[Afiqah Abu Samah]

Thanks for answering my ques. the above equation is for wavelet energy. Why can't I get the same answer when I used wenergy2 function and when I used the code you wrote above?