u/? x=2x,? u/? y=0
v/? x=0,? v/? y=2y
According to Cauchy Riemann equation:
u/? x=? v/? y→2x=2y→x=y
u/? y=-? v/? X is established
So f(z) is differentiable on the straight line y = x.
But f(z) is not differentiable at any point outside the straight line,
The analysis of f(z) at a certain point requires that it can be differentiated in a neighborhood of that point, so f(z) is not analyzed anywhere in the z plane.