Complex Fourier series has a singular term

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Homework Help Overview

The discussion revolves around finding the complex Fourier series for the function f(t) = t(1-t) over the interval (0, 1). Participants are exploring the implications of a singular term that arises when calculating the Fourier coefficients.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of the Fourier coefficients, particularly noting the singularity at n=0. There is an exploration of whether this indicates that the complex Fourier series does not exist or if there is a workaround. Some participants suggest alternative methods for handling the n=0 term.

Discussion Status

The discussion is active, with participants sharing insights and clarifications regarding the calculation of c_0. Some have provided guidance on how to approach the integration differently to avoid the singularity issue, while others express curiosity about the underlying principles of the complex Fourier series.

Contextual Notes

Participants are navigating the constraints of the problem, particularly the behavior of the Fourier coefficients and the implications of the singular term. There is a focus on understanding the treatment of the n=0 term in the context of complex Fourier series.

Ragnord
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Homework Statement



Find the complex Fourier series for f(t)=t(1-t), 0<t<1

Homework Equations



[tex]\sum_{n=-\infty}^{\infty}c_{n}e^{2in\pi t}[/tex]

where [tex]c_{n}=\int_{0}^{1}f(t)e^{-2in\pi t}dt[/tex]


The Attempt at a Solution



I've worked out that c[tex]_{n}=-1/(2n^2 \pi^2)[/tex]. The problem is that for n=0, it is singular. Is there some way around this or does it mean that the complex Fourier series doesn't exist?
I tried using maple to graph the series with the n=0 term omitted and it comes out to the right shape, but is shifted vertically down some, leading me to believe that the singular term should be replaced by a constant or something.
 
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[tex]c_0=\int_0^1 f(t)\,dt[/tex]
 
Well that was easy, just like a real Fourier series. Thanks.
I'm interested in knowing why that's the case though, I haven't seen anything about doing anything special for [tex]c_{0}[/tex] in anything I've seen about complex Fourier series.
 
Just plug in n=0 before integrating instead of after!
 

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