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Thread: Hexus.Help.Maths-Coursework :p (Fourier Series)

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    Hexus.Help.Maths-Coursework :p (Fourier Series)

    Anyhting that involves Fourier is gay. Everyone knows this. But...

    Compute the Fourier series representation of

    f(x) = exp(ax), -pi <= x < pi.
    Got the a0 term:

    (sinh(a*pi))/(a*pi)

    For an and bn i just keep going roun in circles for the integration by parts and splitting it up with different limits, evena nd odd functions etc isnt helping

    Any ideas?
    Twigman

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    radix lecti dave87's Avatar
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    If I understood what that meant, I'd help. But I dont, so i suggest teh following:

    Click Here

    Sorry, had to be done

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    Cheer for the useful replies
    Still as clueless as i was before tbh.
    Twigman

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    Ok..well its to do with the exponential trig identities.
    (im an engineer so j is imaginary...learn to cope with it )

    cos(nx) = { exp(jnx) + exp(-jnx) } / 2
    and equivalent for sin,
    and
    exp(pi*j) = -1
    (and exp(-pi*j) = 1)

    but still i just get a mass of crap and i dont really know how to simplify it...

    MATHS IS OFFICIALLY TEH GAY!!!!1111
    Twigman

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    Treasure Hunter extraordinaire herulach's Avatar
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    all that says is cos(pi*i) = 0, which im not sure is true anyway.
    what you actually mean is the integral -pi to pi is 0, whcih is not the same

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    Treasure Hunter extraordinaire herulach's Avatar
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    writing it out, its not that difficult an integration, use the exponential identites, multiply by your initially function (rembering that exp(ax)*exp(bx) = exp((a+b)x) and it really isnt that difficult to integrate.

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    Quote Originally Posted by herulach
    all that says is cos(pi*i) = 0, which im not sure is true anyway.
    Where did you get that from? stupid maths person
    what you actually mean is the integral -pi to pi is 0, whcih is not the same
    ...?
    What?
    integral of what? integral of sin is 0 yeah...as is cos...

    its not the integration part that screws me over...its once you have done that, put in the limits...simplifying it seems to be beyond me

    Cheers for the advice anyway.
    Twigman

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