Complex operator in polar coords

demidemi
Messages
3
Reaction score
0

Homework Statement


If z=x + iy, what is d/dz in polar coordinates?


The Attempt at a Solution



I know that expanded,

d/dz = 1/2 (d/dx) - i (d/dy)

Where to go from there?
 
Physics news on Phys.org
Use the chain rule:

You have
\frac{df}{dz}= \frac{\partial f}{\partial x}+ \frac{\partial f}{\partial y}i
= \left(\frac{\partial f}{\partial r}\frac{\partial r}{\partial x}+ \frac{\partial f}{\partial \theta}\right)+ \left(\frac{\partial f}{\partial r}\frac{\partial r}{\partial y}+ \frac{\partial f}{\partial \theta}\frac{\partial \theta}{\partial y}\right)i

with, of course, r= \sqrt{x^2+ y^2} and \theta= arctan(y/x).
 
Why is "f" necessary there?

Also, should there be a "partial theta partial x" in the first parentheses?
 
Last edited:
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top