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Matlab syntax help using fourier series & vectors

  1. Jan 26, 2009 #1
    I'm trying to understand some matlab code. It's the fourier series approximation of a signal. This is my first time using matlab, so I guess I'm really trying to comprehend the syntax.

    For my example, I am using some code I googled (http://www.ee.nmt.edu/~wedeward/EE341/FA97/example8.html)

    Code (Text):

    01 N = 11;                            % summation limit (use N odd)
    02 wo = pi;                           % fundamental frequency (rad/s)
    03 c0 = 0;                            % dc bias
    04 t = -3:0.01:3;                     % declare time values
    05
    06 yce = c0*ones(size(t));            % initialize yce to c0
    07
    08 for n = -N:2:N,                    % loop over series index n
    09   cn = 2/(j*n*wo);                 % Fourier Series Coefficient
    10   yce = yce + cn*exp(j*n*wo*t);    % Fourier Series computation
    11 end
     
    What I don't understand is the yce = yce + .... line (line 10). On that line you have
    yce [vector]
    cn [scalar]
    j [scalar]
    n [scalar]
    wo [scalar]
    t [vector]

    So what does
    vector = vector + scalar * exp(scalar * scalar * scalar * vector)
    really evaluate to in matlab?

    Does exp(vector) really mean it creates a new vector with entries:
    e^old_vec_entry_for_t0
    e^old_vec_entry_for_t1
    ....
    e^old_vec_entry_for_tn

    If so, then it makes sense as then it resolves to
    vector = vector + scalar*vector

    which is then

    vector_running_sum = vector_running_sum + vector_values_for_all_t_from_neg_n_to_pos_n
     
    Last edited: Jan 26, 2009
  2. jcsd
  3. Jan 27, 2009 #2

    MATLABdude

    User Avatar
    Science Advisor

    Your interpretation is correct. When you do vectorB=exp(vectorA), it produces a vector of the same size as vectorA containing the exponents of each of the values in vectorA.

    This is an element-wise operator. Sometimes, you need to specify (usually by preceding the operator with a period, for instance ./ is element-wise division). For more, see:
    http://www.cyclismo.org/tutorial/matlab/operations.html
     
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