Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

DFT Matlab function

  1. Mar 4, 2010 #1
    I've been asked to write a function (.m file) in Matlab to calculate the discrete fourier transform coefficient for an arbitrary function x. So far this is what I've done:

    function a = mydft(x,N)
    %MYDFT Calculates the discrete fourier transform
    %usage:
    %[a]=mydft(x)
    %x=[ x[0] x[1] ... x[N-1] ] - vector containing discrete time sequence
    %a=[ a_0 a_1 ... a_N-1 ] - vector of discrete time Fourier Series
    %coefficients, k=0,...,N-1
    for k=0:N-1
    for m=0:N-1
    w=exp(-j*2*pi/N.*m.*k);
    end
    a=sum(x(m).*w);
    end
    end

    when I use it on a signal given to me and then plot kw_hat vs. |a| I get a plot that looks nothing like what I do for the same signal by hand. I don't think I'm getting the correct DFT coefficients out of this function

    This is the first time I've used Matlab so I'm not very familiar with it and would appreciate any advice.
     
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted