How to find the fourier transform of exp(-|x|)

In summary, the student is trying to solve the Fourier transform of exp(-|x|) and is unsure if they need to split the function into two parts with different limits. The responder suggests breaking the integration into two parts due to the nature of |x| being equal to -x for negative values of x. The student understands and thanks the responder for their clarification.
  • #1
samdawy
7
0

Homework Statement



I have been trying to solve the Fourier transform of exp(-|x|)


Homework Equations



Do I need to split the function into two parts with different limits,i.e. the first has a limit from -infinity to zero and the secod from zero to +infinity. Please advise?

The Attempt at a Solution

 
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  • #2
samdawy said:
Do I need to split the function into two parts with different limits,i.e. the first has a limit from -infinity to zero and the secod from zero to +infinity. Please advise?

That sounds like a good plan to me :smile:...what do you get when you d that?
 
  • #3
To be honest, I just assumed the exp(-|x|) is equal to exp(-x) for x between the minus and positive infinity and did the normal integration. Am I in the right track?
 
  • #4
Well, |x| is equal to -x for negative values of x isn't it?...And so in the interval -inf to 0, exp(-|x|)=exp(+x)...that is why you need to break the integration into two parts.
 
  • #5
should not |x| for any negative value equal to +x ?

sorry but I am a little bit confused,
 
  • #6
if x is negative, then +x is also negative isn't it?:wink:

For example, let's look at x=-2...clearly +x=-2 while -x=+2 so |x|=-x in this case since |-2|=2...do you follow?
 
  • #7
Yah, I got it

I really thank you for you clarification
 

1. How do I find the Fourier transform of exp(-|x|)?

The Fourier transform of a function f(x) is given by F(k) = ∫f(x)e^(-ikx)dx. In this case, we have f(x) = exp(-|x|), so F(k) = ∫exp(-|x|)e^(-ikx)dx. We can use the properties of the Fourier transform and the fact that exp(-|x|) is an even function to simplify this integral and obtain the solution F(k) = 2/(1+k^2).

2. Is there a specific method for finding the Fourier transform of exp(-|x|)?

Yes, there are several methods for finding the Fourier transform of a function. One approach is to use the definition of the Fourier transform and evaluate the integral directly. Another method is to use the properties of the Fourier transform, such as linearity and even/odd symmetry, to simplify the integral. In this case, using the properties of the Fourier transform would be the most efficient approach.

3. Can the Fourier transform of exp(-|x|) be calculated using software?

Yes, there are many software programs available that can calculate the Fourier transform of a given function. Some popular options include MATLAB, Mathematica, and Python's NumPy library. These programs have built-in functions or libraries that can compute the Fourier transform numerically.

4. How is the Fourier transform of exp(-|x|) used in applications?

The Fourier transform is a powerful tool in mathematics, physics, and engineering. In particular, the Fourier transform of exp(-|x|) has applications in signal processing, image processing, and quantum mechanics. It can also be used to solve differential equations involving exp(-|x|) and to analyze the behavior of exp(-|x|) in the frequency domain.

5. Is the Fourier transform of exp(-|x|) related to any other mathematical concepts?

Yes, the Fourier transform is closely related to other mathematical concepts, such as the Laplace transform and the Mellin transform. These transforms share similar properties and can be used to solve problems in different areas of mathematics. The Fourier transform of exp(-|x|) is also related to the Cauchy distribution, which has applications in probability and statistics.

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