Solving Integral: Defining Branch Cut Prior

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SUMMARY

The discussion focuses on defining the branch cut for the integral of [log x]^4 / [1+x^2] from 0 to infinity. It is established that placing a branch cut along the negative real axis is essential for proper integration. The integration process involves avoiding the singularity at z=0 with a small arc and closing the contour with a larger arc. Additionally, it is advised to analyze lower powers of log(x) before tackling log(x)^4 to simplify the problem.

PREREQUISITES
  • Complex analysis concepts, specifically contour integration
  • Understanding of branch cuts in complex functions
  • Familiarity with logarithmic functions and their properties
  • Knowledge of poles and residues in complex analysis
NEXT STEPS
  • Study the principles of contour integration in complex analysis
  • Learn about branch cuts and their implications in complex functions
  • Explore the properties of logarithmic functions in complex variables
  • Investigate the residue theorem and its applications in evaluating integrals
USEFUL FOR

Students and professionals in mathematics, particularly those studying complex analysis, as well as anyone involved in solving integrals with branch cuts and singularities.

logmarie
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Homework Statement


Define the branch cut prior to solving the following:
integrate from 0 to infinity of [log x]^4/ [1+x^2]


Homework Equations



The only poles inside the upper half plane is i

The Attempt at a Solution



How do I separate the countour?---help.

Thanks.
 
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Just put a branch cut along the negative real axis. Now integrate along the real axis avoiding the singularity at z=0 with a little arc and closing in a big arc. I think you need to work out the lower powers of log(x) before you go direct to log(x)^4, but there may be a trick.
 

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