Can the Residue Theorem be applied to these contour integrals?

In summary, the conversation discusses a question on contour integration and the use of the residue theorem. It also mentions the need for poles to be inside the contour for it to be applicable. The conversation also suggests learning LaTeX for easier formatting.
  • #1
itsnogood
1
0
Hi, first post here. I'm having some trouble with contour integration. Basically here's the question:

Contour Integral of

1+z dz
(z-1)(z2+9)

There are three cases:

l z l = 2
l z+1 l = 1
l z-[itex]\iota[/itex] l = 3

Is each case a straightforward application of the residue theorem? Also, reading up in my textbook the poles should be contained within the contour so does on the boundary count?

Thanks in advance.
 
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  • #2
itsnogood said:
Hi, first post here. I'm having some trouble with contour integration. Basically here's the question:

Contour Integral of

1+z dz
(z-1)(z2+9)
You should take a little time and learn LaTeX. It's not very difficult.
$$\int_C \frac{1+z}{(z-1)(z^2+9)}\,dz$$
There's a good tutorial here: https://www.physicsforums.com/showthread.php?p=3977517#post3977517

There are three cases:

l z l = 2
l z+1 l = 1
l z-[itex]\iota[/itex] l = 3

Is each case a straightforward application of the residue theorem?
Yup.

Also, reading up in my textbook the poles should be contained within the contour so does on the boundary count?
No, the pole needs to be inside the contour. If it's on the contour, you have to treat it differently.
 

1. What is the Residue Theorem?

The Residue Theorem is a mathematical concept in complex analysis that allows for the evaluation of integrals along closed curves by using the residues (singularities) of a function within the enclosed region.

2. How is the Residue Theorem used in real-world applications?

The Residue Theorem has various applications in physics, engineering, and other fields. It is commonly used to solve problems related to electric circuits, fluid dynamics, and quantum mechanics.

3. What are the key steps in applying the Residue Theorem?

The key steps in applying the Residue Theorem include identifying the singularities of the function within the enclosed region, calculating the residues at each singularity, and using the residue values to evaluate the integral.

4. Are there any limitations to using the Residue Theorem?

Yes, there are limitations to using the Residue Theorem. It can only be applied to integrals along closed curves, and the function must have singularities within the enclosed region. It also requires knowledge of complex analysis and the ability to calculate residues.

5. Can the Residue Theorem be used for integrals with multiple variables?

No, the Residue Theorem is only applicable for integrals with one complex variable. It cannot be used for integrals with multiple variables, such as double or triple integrals.

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