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!

I Question about fitting periodic data

  1. Apr 22, 2016 #1
    My experience with data fitting is poor so I am in real need for help.
    The potential in the following is periodic over [0,Pi]
    I need to find a fitting function that I can use to perform further mathematics. Fourier series does not work, but a 40-degree polynomial give the following fit
    However, the polynomial does not preserve its periodicity over the cycle. Could someone please advice what I should do to get a good fitting function for my data?
  2. jcsd
  3. Apr 22, 2016 #2
    Fitting with a polynomial with degree larger than 3 is a really bad idea.

    Why don't you try to fit this function with a combination of straight lines?? And why do Fourier series not work?
  4. Apr 22, 2016 #3


    User Avatar
    2017 Award

    Staff: Mentor

    A set of straight lines for different ranges should fit best. A Fourier series should give reasonable approximations, but only if you include many terms.
  5. Apr 23, 2016 #4


    User Avatar
    Science Advisor

    Looking at the vertical scale: Is your data set really constricted to the value -9.74771?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted