Fourier Series - Am I Crazy or is My Teacher Tricking Me?

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Homework Help Overview

The original poster is working on a problem involving the Fourier series approximation of the function f(θ) = tan(θ) over the interval from θ = -π/2 to π/2. The task is to find the first three terms of the series.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the coefficients a0, a1, and b1 for the Fourier series but expresses frustration over the results being zero. They question whether the undefined nature of tan(θ) at the endpoints affects their calculations.
  • Another participant raises questions about the properties of odd and even functions in relation to the presence of cosine and sine terms in the Fourier series.

Discussion Status

The discussion is ongoing, with participants exploring the implications of the function's properties on the Fourier series terms. There is no clear consensus yet, but questions about function characteristics and their effects on the series are being examined.

Contextual Notes

The original poster notes the potential issue with tan(θ) being undefined at the endpoints of the interval, which may influence their approach to the problem.

mundane
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I am SO annoyed with this problem. Ready to jump out a window.

Homework Statement



Find the first three terms of the Fourier series that approximates f(θ) = tan(θ) from θ = -π/2 to π/2.

The Attempt at a Solution



So, I know that for an equation on [[itex]\frac{-b}{2}[/itex], [itex]\frac{b}{2}[/itex]], to define the Fourier series for that equation we use f(x)={a0+a1cosx+a2cos2x+ ... +b1sinx+b2sin2x+ ...}

I only need to find the first three terms, so its just a0+a1cosx+b1sinx.

a0 is defined as [itex]\frac{1}{\pi}[/itex][itex]\intf(x)dx[/itex] definite integral from -π/2 to π/2.

a1 is defined as [itex]\frac{2}{\pi}[/itex][itex]\int\f(x)cos(2πx/π)dx[/itex] definite integral from -π/2 to π/2.

b1 is defined as [itex]\frac{2}{\pi}[/itex][itex]\int\f(x)sin(2πx/π)dx[/itex] definite integral from -π/2 to π/2.For a0, my antiderivative was -log(cos(x)). After substitution, a0=0.

For a1, my antiderivative was log(cos(x))-(1/2)cos(2x). After substitution, a1=0.

I have not done b1 yet. Am I being trolled?

Does this ave something to do with the fact that tan(x) is undefined at those two interval points? Am I going in the wrong direction?
 
Physics news on Phys.org
If a function is odd, can it have cosine terms?
If a function is even, can it have sine terms?
 
Sorry, I didn't mean to repost. I was trying to change the red font and it reposted. Sorry.
 

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