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Homework Help: Octave partial fraction decomposition help!

  1. Oct 21, 2012 #1
    So I'm trying to figure out how to decompose the following using octave:

    85000/[(s^2+250^2)(0.2s^2+40s+10000)]

    I tried using the residue command but I think that only works if the polynomials have real roots, which these don't. When I do use residue I get the following:
    b =

    2.0000e-01 4.0000e+01 2.2500e+04 2.5000e+06 6.2500e+08

    octave:29> [r p k e] = residue(85000,b)
    r =

    -0.016000 + 0.004000i
    -0.016000 - 0.004000i
    0.016000 - 0.013000i
    0.016000 + 0.013000i

    p =

    0.00 + 250.00i
    -0.00 - 250.00i
    -100.00 + 200.00i
    -100.00 - 200.00i

    k = [](0x0)
    e =

    1
    1
    1
    1

    <b> being (s^2+250^2)(0.2s^2+40s+10000) only expanded

    The answer I get using wolfram, which is correct, is:

    (1.68+0.0064 s)/(10000.+40. s+0.2 s^2)+(-2.-0.032 s)/(62500.+1. s^2)

    Is there any way I can get octave/matlab to decompose it into like that ^^^^

    Or better yet, is there a way I can deduce that ^^^^^ from the answer octave/matlab gives me?

    Thanks for any help, if you need clarification just ask.
     
  2. jcsd
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