## gerryliyana Group Title prove that the function f(z) = Re(z) does not have a derivative for any value of z one year ago one year ago

1. gerryliyana

@phi @Hero @jhonyy9

2. Xavier

Use the limit definition of the derivative and you have it approaching different values along different lines

3. gerryliyana

how to prove it using philosophy of course very deeply??

4. sirm3d

use Cauchy-Riemann conditions for differentiability. $\newcommand {pd}{\partial}\frac{\pd u}{\pd x}=\frac{\pd v}{\pd y},\qquad \frac{\pd u}{\pd y}=-\frac{\pd v}{\pd x}$ given $f(z)=u(x,y) + v(x,y)i$

5. sirm3d

let $z=x+yi$ $f(z)= \text{Re } z=x+0i$

6. sirm3d

$u_x=1,v_y=0$ the first condition is not satisfied.

7. gerryliyana

@sirm3d did you know symmetric tops of molecule??