How Does the Complex Logarithm Function Differ Across Branches?

  • Thread starter Thread starter neginf
  • Start date Start date
  • Tags Tags
    Log
Click For Summary
SUMMARY

The discussion focuses on the complex logarithm function, specifically examining the equations log(i^2) = 2*log(i) and log(i^2) <> 2*log(i) under different ranges for theta. It establishes that log(i) equals i * π/2, leading to log(i^2) equating to i * π. The ranges for theta indicate that the logarithm's behavior changes based on the specified intervals, highlighting the multi-valued nature of the complex logarithm. This analysis confirms the importance of considering the branch cuts in complex analysis.

PREREQUISITES
  • Understanding of complex numbers and their representations
  • Familiarity with the complex logarithm function
  • Knowledge of polar coordinates and Euler's formula
  • Basic grasp of branch cuts in complex analysis
NEXT STEPS
  • Study the properties of the complex logarithm function in detail
  • Learn about branch cuts and their implications in complex analysis
  • Explore the concept of multi-valued functions in mathematics
  • Investigate the application of Euler's formula in complex number calculations
USEFUL FOR

Mathematics students, educators, and anyone interested in advanced topics in complex analysis, particularly those studying the properties and applications of complex logarithms.

neginf
Messages
56
Reaction score
0

Homework Statement



Show that

(a) log(i^2) = 2*log(i) when log z=ln r + i * theta (r>0 and pi/4 < theta < 9*pi/4)
(b) log(i^2) <> 2*log(i) when log z=ln r + i * theta (r>0 and 3*pi/4 < theta < 11*pi/4)

Homework Equations



log z = ln r + i * theta

The Attempt at a Solution



Got log(i) = i * pi/2
log(i^2)= i * pi.
Are those right ?

Do not know what to do with ranges given for theta.
 
Last edited:
Physics news on Phys.org
You're assuming i = eiπ/2, but you also have i = ei(π/2+2π) = ei(π/2+4π) and so on. Now do you see what the problem is getting at?
 

Similar threads

Replies
5
Views
2K
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K