You can evaluate the partial derivatives with the function as Mr. Fantastic showed you, or else realize (most books have it) that the CR-equations
are equivalent to , where we have that , so putting , we get:
.
Check the above and conclude your function is analytic in
Tonio
A thread of related interest: http://www.mathhelpforum.com/math-he...erivation.html
(And a correction of a minor typo in red).