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

Trapezoidal Integral of Discrete Values

  1. Apr 5, 2014 #1
    Hi guys, so I'm trying to create this thing that gets accelerometer values and integrate those values at about 25 samples a second. From what I understand if I integrate the values, that means each second I have 25 values I want to integrate. I read this research paper where someone used the trapezoidal integration to do it but I've been trying to read up on it and I guess I'm having some problems. Firstly can I use the trapezoidal integration to do it?

    Secondly this is the equation they used:
    y(n) = y(n-1) + (1/(2fs))*(x(x-1)+x(n)) , where n>0

    so I guess fs is my sampling frequency which would be 25 and x is my integrand. I would assume n is my value so 1 or 2 or 3rd sample but I'm worried about y(n-1) and the x(n) part since the start of the equation is y(n).

    Basically if say my values were
    Fs=25
    n=1
    x= 32

    then is it right to say
    y(n) = y(1-1) + (1/(2*25))*(32(32-1)+32(1))
    or is the y(n-1) similar to the y(n) part and I have to sort of work out the integration together?

    Also with my second sample do I just add it to my first? Apologies about this, my maths isn't the best.
    Lastly is the equation I wrote make sense? I tried looking up similar trapezoidal equations and the look similar to me.
     
  2. jcsd
  3. Apr 6, 2014 #2

    mathman

    User Avatar
    Science Advisor
    Gold Member

    You should describe what you are trying to calculate. Also your description has several typos, which should be fixed for clarity.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Trapezoidal Integral of Discrete Values
Loading...