D[f, {list, n}] is equivalent to D[f, {list}, {list}, ...] where {list} is repeated times. If is a scalar, a list has depth 1, then the result is a tensor of rank , as in the term of the multivariate Taylor series of .
D[f, {list1}, {list2}, ...] is normally equivalent to First[Outer[D, {f}, list1, list2, ...]].
Numerical approximations to derivatives can be found using N.
D uses the chain rule to simplify derivatives of unknown functions.
D[f, x, y] can be input as . The character \[InvisibleComma], entered as Esc , Esc, can be used instead of an ordinary comma. It does not display, but is still interpreted just like a comma.