[R] g(x,y) = f(x,y) - e(x)- e(y)?

[William Simpson]

Hi everyone,

The following is mysterious to me. David Brillinger (famous
statistician at Berkeley) has an equation in a paper that is
essentially
g(x,y) = f(x,y) - e(x)- e(y)
These are continuous functions. I am not sure how to do this with the
discrete equivalents in R.
Please tell me how to do what he means in R.

Thanks very much for any help!

Bill