Complex Analysis Fun: Analytic Antiderivatives in {z:|z|>2}

Click For Summary
SUMMARY

The function \(\frac{z}{(z-1)(z-2)(z+1)}\) has an analytic antiderivative in the region \(\{z \in \mathbb{C}: |z| > 2\}\). The discussion also explores whether replacing \(z\) with \(z^2\) in the numerator affects the existence of an analytic antiderivative in the same region. Participants suggest using partial fraction decomposition and logarithmic functions to analyze the problem, emphasizing the importance of branch cuts in determining the validity of the antiderivative.

PREREQUISITES
  • Complex analysis fundamentals
  • Partial fraction decomposition techniques
  • Understanding of analytic functions
  • Knowledge of branch cuts in complex integration
NEXT STEPS
  • Study the properties of analytic functions in complex analysis
  • Learn about partial fraction decomposition in complex variables
  • Explore the concept of branch cuts and their implications in integration
  • Investigate the use of logarithmic functions in complex analysis
USEFUL FOR

Students and professionals in mathematics, particularly those focusing on complex analysis, as well as anyone interested in understanding analytic functions and their antiderivatives.

Mystic998
Messages
203
Reaction score
0

Homework Statement


Show that \frac{z}{(z-1)(z-2)(z+1)} has an analytic antiderivative in \{z \in \bold{C}:|z|>2\}. Does the same function with z^2 replacing z (EDIT: I mean replacing the z in the numerator, not everywhere) have an analytic antiderivative in that region?


Homework Equations


Um lots of things I imagine.


The Attempt at a Solution


Well, I'm pretty sure that I can do a partial fraction decomposition in both cases, then the appropriate logarithms would give me a function that's analytic on the region minus whatever line I do the branch cut on. But unless there's some huge typo in the problem, I don't think that's what's being sought. I'm not really sure what else to do in this situation though. I have some other thoughts on the problem that may or may not work, but they're kind of long winded, and I'd rather not go into them unless I really have to. So, any suggestions?
 
Last edited:
Physics news on Phys.org
Well, I still haven't been able to come up with anything. I thought maybe I could use specific branch cuts of log to show that the partial fraction decomposition integrates to zero around any closed curve in the region (I think it would require different branch cuts for each integral, so I don't know how valid this is), but then I have a problem if the closed curve has the complement of my region "inside" it.
 

Similar threads

  • · Replies 17 ·
Replies
17
Views
4K
Replies
8
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
1
Views
2K
Replies
7
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
4
Views
2K