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

[Twigman]

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?

[dave87]

If I understood what that meant, I'd help. But I dont, so i suggest teh following:

Click Here

Sorry, had to be done

[Twigman]

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

[Twigman]

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

[herulach]

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

[herulach]

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.

[Twigman]

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.