I have tried to find the Fourier series for a function [itex]u(x)[/itex]:(adsbygoogle = window.adsbygoogle || []).push({});

[tex]

u(x)=\sin((1+3\cos(t))t)

[/tex]

The function is odd, hence the Fourier coefficients [itex]a_n[/itex] equal zero and the [itex]b_n[/itex]s are given as

[tex]

b_n=\frac{4}{T}\int_0^{T/2}u(t)\sin(n\omega t)\,\text{d}t

[/tex]

where [itex]T=2\pi[/itex] and [itex]\omega=2\pi/T=1[/itex].

Then, my problem is that u(x)*sin(n*t) is not easily integrated. I would then like to ask if there could be any way getting around this integration-problem, perhaps if I wrote u(x) as either the real og imaginary part of a complex function? I would appreciate any help.

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# Fourier series

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