Calculating Antiderivative of Complex Integral

In summary, To calculate the Fourier transform encountered in reading quantum physics, the antiderivative of \frac{e^{-iz}}{z^2+(\mu r)^2} must be calculated. This involves complex analysis, for which there are many resources available, including undergraduate complex analysis texts and mathematical methods books. One recommended book is Mary Boas' "Mathematical Methods for the Physical Sciences." The calculation of the antiderivative can be related to the residue theorem, and the condition |e^{itz}| \leq 1 is required for the integral formula to be used.
  • #1
rar0308
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Homework Statement


z is a complex variable.
What is antiderivative of [itex]\frac{e^{-iz}}{z^2+(\mu r)^2}[/itex]?



Homework Equations





The Attempt at a Solution


To caluculate the Fourier transform encounterd in reading quantum phsycis i have to calcualte this integral. I have little knowledge of complex analysis. How can I do this? And please recommend books in which this thing can be found.
 
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  • #2
What are we antidifferentiating with respect to? I'm also assuming you mean AN antiderivative, or the general form of all antiderivatives.
 
  • #3
It's respect to z.
 
  • #4
The integral you presumably want is related by a change of variables to the one computed here http://en.wikipedia.org/wiki/Residue_theorem#Example (it seems as clear as anything I would write). Give that a read through and post back with specific questions here. This is covered in almost every undergrad complex analysis text, as well as in most math methods texts.
 
  • #5
Very helpful
I read it.
Is [itex]Res_{z=i}f(z)=\frac{e^{-t}}{2i}[/itex] calculated by Cauchy's integral formula?
Why is the condition
[itex]
|e^{itz}| \leq 1
[/itex] required?

I'm reading quantum physics book. Fourier transforms appears in the book frequently. Which math book is good for learing introductory complex analysis so that there is no problem in doing quantum physics? Other than mathematical method books which is so brief .
 
Last edited:
  • #6
rar0308 said:
Very helpful
I read it.
Is [itex]Res_{z=i}f(z)=\frac{e^{-t}}{2i}[/itex] calculated by Cauchy's integral formula?

Well, the residues should really be thought of as ingredients in the residue theorem, which is a generalization of the integral formula. However, in the case here, the poles in the function are sufficiently obvious that you can use the integral formula to compute the contour integral directly.

Why is the condition
[itex]
|e^{itz}| \leq 1
[/itex] required?

It's required so that

[tex]\int_{\mathrm{arc}}{|e^{itz}| \over |z^2+1|}\,|dz| \leq \int_{\mathrm{arc}}{1 \over |z^2+1|}\,|dz|[/tex]

in the argument that the contribution to the integral from the arc vanishes.

I'm reading quantum physics book. Fourier transforms appears in the book frequently. Which math book is good for learing introductory complex analysis so that there is no problem in doing quantum physics? Other than mathematical method books which is so brief .

I haven't looked at it much myself, but the book that's always recommended for undergrads is Mary Boas "Mathematical Methods for the Physical Sciences." I've used Arfken's math methods book, but it's geared towards grad students and is more of a reference book.
 

1. What is an antiderivative?

An antiderivative, also known as an indefinite integral, is the reverse operation of differentiation. It is a function that, when differentiated, gives the original function as its result.

2. How do you calculate the antiderivative of a complex integral?

To calculate the antiderivative of a complex integral, you can use the rules of integration, such as the power rule, product rule, and chain rule. It is important to follow the proper steps and use the correct substitutions when necessary.

3. What is the difference between a definite and indefinite integral?

A definite integral has specific limits of integration, while an indefinite integral does not. This means that a definite integral gives a numerical value, while an indefinite integral gives a function as its result.

4. Can any function have an antiderivative?

No, not all functions have an antiderivative. A function must be continuous and have a continuous derivative in order to have an antiderivative. Also, some functions, such as transcendental functions, do not have an algebraic antiderivative.

5. How do you check if a calculated antiderivative is correct?

You can check the correctness of a calculated antiderivative by differentiating it and seeing if the result matches the original function. If it does, then the antiderivative is correct. You can also use online tools or graphing calculators to verify the result.

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