1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Fourier Series Proof

  1. Nov 2, 2005 #1
    Show that
    [tex] \lim_{n \rightarrow \infty} \int_{0}^{\pi} Ln(x) Sin(nx) dx [/tex]

    i was told to use this identity
    given that [itex] int f^2 \rho dx [/itex] is finite then
    [tex] c_{n}^2 \int_{a}^{b} \phi_{n}^2 \rho dx = \frac{(\int_{a}^{b} f \phi_{n} \rho dx)^2}{\int_{a}^{b} \phi_{n}^2 \rho dx} \rightarrow 0 [/tex] and n approaches infinity

    here Cn are the Fourier Coefficients

    but how do i relate this to the problem i have
    would rho = log x and phi^2 = sin nx?
    Please help!
    Last edited: Nov 2, 2005
  2. jcsd
  3. Nov 3, 2005 #2
    can anyone help with this question?

    how would you go about solving it given the 'stuff' i have shown?

    Thank you in advance for your help!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook