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Help in interpreting a graph -

  1. Sep 4, 2006 #1
    help in interpreting a graph - URGENT

    hello!

    i obtained this graph after a study
    could anyone please help me in interpreting it
    like
    i want to know whether it follows any definite pattern
    any arithematic,geometric progression or a parabolic equation or anything??

    thank you

    nave
     

    Attached Files:

  2. jcsd
  3. Sep 4, 2006 #2
    It looks periodic, so you could express it as a sum of sine and cosine functions.
     
  4. Sep 4, 2006 #3
    how do i do that??
    is there anything being formed
    could you state it

    do you want more data
    i could forward to you my data
    some more information
    would that help??
     
    Last edited: Sep 4, 2006
  5. Sep 4, 2006 #4
    Look up Fourier transforms.
     
  6. Sep 4, 2006 #5

    J77

    User Avatar

    You could do some time-delay embedding.

    Looks quasiperiodic from the limited data you have.
     
  7. Sep 4, 2006 #6
    I can upload the actual data .
    The data has a periodicity of 19 years. But in between it seems disjointed. The sequence is like this :
    9
    28
    18
    8
    26
    15
    4
    23
    11
    0
    19
    9
    27
    17
    6
    25
    13
    2
    21
    9
    28
    18
    7
    26
    15
    4
    22
    12
    0
    19
    9
    28
    16
    6
    24
    13
    2
    21
    10
    29
    18
     
  8. Sep 4, 2006 #7
    Uh.Huh. It is beyond me!!!
     
  9. Sep 4, 2006 #8
    What? You asked for suggestions without telling us anything about what you want to do, or the level of math you're comfortable with, and we've accordingly given you suggestions.
     
  10. Sep 4, 2006 #9
    I am 12th grade student from India. I have obtained this data for a project . I am comfortable with trignometry , Calculus etc. But I can learn Fourier transforms if it helps me interpret the data effectively. Please give your suggestions. And thanks for the follow-up.
     
  11. Sep 4, 2006 #10

    J77

    User Avatar

    Is that all the data you have?

    What results do you want?

    Graphically, look up the delay-embedding, in say, Yorke, Alligood and Yorke - Introduction to dynamical systems and chaos (I think that's the title.)

    I don't think there's enough data for a spectral analysis using ffts...
     
  12. Sep 4, 2006 #11
    I am studying the new moons dates while it transits a particular constellation from 2000-2040. I wish to know if an equation can be derived to arrive at the dates say 2100 for similar star positions using this formulae .
     
  13. Sep 4, 2006 #12
    another graph

    hope this helps
     

    Attached Files:

    Last edited: Sep 4, 2006
  14. Sep 4, 2006 #13

    CRGreathouse

    User Avatar
    Science Advisor
    Homework Helper

    I recommend looking at the data modulo small integers -- say 10 through 60. See if anything comes up. That will help you fit it to a modified sine curve, or at least show potential problems of doing so.
     
  15. Sep 4, 2006 #14
    could you elaborate more on that
     
  16. Sep 4, 2006 #15

    CRGreathouse

    User Avatar
    Science Advisor
    Homework Helper

    Sure. For made-up data points (31, 1), (41, 10), (51, -5), (61, 1), (81, -5), (101, 10) you'll notice that when x is 1 mod 30 there's one value, when x is 11 mod 30 there's another, and when x is 21 mod 30 there's a third. Just transform your data so it's all in the form (a*n + b, y) with some fixed y in the suggested range (roughly, the expected period) and see how similar y values are across points with the same b values. If the data are periodic, there should be some choice of n that makes them line up perfectly; if they are near-periodic, then some choice of n should make them line up well (perhaps with a little bit of correlation with the a value, perhaps with just random variation).
     
  17. Sep 4, 2006 #16
    if you use your theory in my graphwhat would be the results???
     
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