Fourier transform - what integral limits

In summary, the Fourier transform of the unit rectangular distribution is ∫-∞∞f(t)e-iωtdt, and the limits for integration can be either -1 to 1 or lim t->-1 to lim t->1. This is because the exponent never vanishes for finite values, and the uniqueness of Fourier transforms states that two functions have the same transform if they differ over a set of points of measure 0.
  • #1
zezima1
123
0
Find the Fourier transform of the unit rectangular distribution f(t) = 1 for ltl<1 else 0
Since e-iωt is zero except for t in ]-1;1[ it must be an integral over this interval. But should I take the boundaries as -1 and 1? Because they are not included in the interval where e-iωt is not zero but rather supremum and infimum for it. Would it better to put the limits lim t->1 and lim t->-1?
 
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  • #2
What?
The exponent never vanishes for finite values.
 
  • #3
umm the Fourier transform is:

-∞f(t)e-iωtdt

But since f(t)=0 for t≥1, t≤-1 you integrate from -1 to 1?
 
  • #4
zezima1 said:
umm the Fourier transform is:

-∞f(t)e-iωtdt

But since f(t)=0 for t≥1, t≤-1 you integrate from -1 to 1?

Yes.
 
  • #5
zezima1 said:
Find the Fourier transform of the unit rectangular distribution f(t) = 1 for ltl<1 else 0
Since e-iωt is zero except for t in ]-1;1[ it must be an integral over this interval. But should I take the boundaries as -1 and 1? Because they are not included in the interval where e-iωt is not zero but rather supremum and infimum for it. Would it better to put the limits lim t->1 and lim t->-1?
I think you meant f(t) where you wrote e-iωt.

Regarding your question about the limits, it turns out it doesn't matter. You can look up some statement about the uniqueness of Fourier transforms. I think it's something like two functions have the same Fourier transform if they differ over a set of points of measure 0.
 

FAQ: Fourier transform - what integral limits

What is the Fourier transform?

The Fourier transform is a mathematical operation that decomposes a function into its constituent frequencies. It is used to analyze the frequency components of a given signal or function.

How is the Fourier transform calculated?

The Fourier transform is calculated by taking the integral of a function over a certain range of frequencies. This integral is known as the Fourier integral.

What are the integral limits in the Fourier transform?

The integral limits in the Fourier transform represent the range of frequencies over which the function is being analyzed. These limits can be any finite or infinite values, depending on the specific function being transformed.

Why are the integral limits important in the Fourier transform?

The integral limits in the Fourier transform determine the range of frequencies that are being analyzed. Different limits can result in different frequency components being identified in the transformed function.

How is the Fourier transform used in science and engineering?

The Fourier transform is used in a wide range of scientific and engineering applications, including signal processing, image and audio compression, and analysis of physical systems. It is a powerful mathematical tool that allows for the analysis of complex functions and signals in terms of their constituent frequencies.

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