- #1
BOAS
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Hello,
I think that I have done this correctly, but this is the first problem I have done on my own and would appreciate confirmation.
1. Homework Statement
Find the Fourier series corresponding to the following functions that are periodic over the interval [itex](−π, π)[/itex] with: (a) [itex]f(x) = 1[/itex] for [itex]−\frac{π}{2} < x < \frac{π}{2}[/itex] and [itex]f(x) = 0[/itex] otherwise.
[/B]
The first coefficient [itex]a_{0} = \frac{1}{\pi} \int^{0.5\pi}_{-0.5\pi} f(x) dx = 1[/itex]
[itex]a_{n} = \frac{1}{\pi} \int^{0.5\pi}_{-0.5\pi} \cos(nx) dx[/itex]
which leads to the following;
[itex]a_{n} = - \frac{1}{n \pi} ((-1^{n}) - 1)[/itex]
[itex]b_{n} = \frac{1}{\pi} \int^{0.5 \pi}_{-0.5 \pi} \sin(nx) dx = 0[/itex]
so my Fourier series is;
[itex]f(x) = 1/2 + \frac{2}{\pi}(\cos(x) - \frac{1}{3}\cos(3x) + \frac{1}{5}\cos(5x) - ... + ) [/itex]
or [itex]f(x) = \frac{1}{2} + \Sigma^{\infty}_{n = 1} (- \frac{1}{n \pi}( (-1)^{n} - 1)) \cos(nx)[/itex]
Does this look ok?
Thanks
I think that I have done this correctly, but this is the first problem I have done on my own and would appreciate confirmation.
1. Homework Statement
Find the Fourier series corresponding to the following functions that are periodic over the interval [itex](−π, π)[/itex] with: (a) [itex]f(x) = 1[/itex] for [itex]−\frac{π}{2} < x < \frac{π}{2}[/itex] and [itex]f(x) = 0[/itex] otherwise.
Homework Equations
The Attempt at a Solution
[/B]
The first coefficient [itex]a_{0} = \frac{1}{\pi} \int^{0.5\pi}_{-0.5\pi} f(x) dx = 1[/itex]
[itex]a_{n} = \frac{1}{\pi} \int^{0.5\pi}_{-0.5\pi} \cos(nx) dx[/itex]
which leads to the following;
[itex]a_{n} = - \frac{1}{n \pi} ((-1^{n}) - 1)[/itex]
[itex]b_{n} = \frac{1}{\pi} \int^{0.5 \pi}_{-0.5 \pi} \sin(nx) dx = 0[/itex]
so my Fourier series is;
[itex]f(x) = 1/2 + \frac{2}{\pi}(\cos(x) - \frac{1}{3}\cos(3x) + \frac{1}{5}\cos(5x) - ... + ) [/itex]
or [itex]f(x) = \frac{1}{2} + \Sigma^{\infty}_{n = 1} (- \frac{1}{n \pi}( (-1)^{n} - 1)) \cos(nx)[/itex]
Does this look ok?
Thanks
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