How Is the Fourier Transform Applied to the Rect Function?

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Discussion Overview

The discussion revolves around the application of the Fourier transform to non-periodic functions, specifically the Rect function and its relationship to the delta function. Participants explore the mathematical implications and computations involved in this context.

Discussion Character

  • Technical explanation, Mathematical reasoning

Main Points Raised

  • Jamie inquires about the application of the Fourier transform to the Rect function and seeks clarification on the topic.
  • One participant distinguishes between Fourier series, which apply to periodic functions, and Fourier transforms, which are relevant for integrable functions.
  • Jamie acknowledges the distinction but asks how to demonstrate that the Fourier transform of the constant function {1} results in a delta function.
  • A later reply suggests a method for computing the Fourier transform by integrating an exponential function over a specified range and hints at the relationship to the delta function without providing a definitive answer.

Areas of Agreement / Disagreement

Participants do not reach a consensus; there are differing views on the application of the Fourier transform and the specifics of the computation involved.

Contextual Notes

The discussion includes assumptions about the behavior of functions as limits approach infinity and the definitions of integrable functions, which remain unresolved.

mr_whisk
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Hi all,

How is the Fourier transform applied to non-periodic functions, such as the Rect function?

Any help would be greatly appreciated,

Cheers,

Jamie :)
 
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I think you are confusing Fourier series, which apply to periodic functions, and Fourier transforms, which apply to integrable (in some sense) functions.
 
OK, i can see why my post appeared to sound like that, but I know what the differnce is.

What i mean is, say, how would you show that the FT transform of {1} is a delta function??

Cheers
 
Let A be a ( large ) positive real number

The transform you specified will lead you to integrate exp( - i * w * t ) with t ranging from -A to A, and letting A approaching +∞. When A approaches +∞, this will give you a function similar to one of these :

http://en.wikipedia.org/wiki/Impulse_function#Representations_of_the_delta_function

I let you try the computation and identify which one corresponds to the Fourier transform of 1.
 

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