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

What kind of formula is this and how is it to be retraced?

  1. Jan 2, 2016 #1
    This is basic maths but I kind of forgot how to retrace such an equation.
    My question is: why does "+-2*xi(n-1)*delta" which is in the middle of the first long equation cancle out? I'm thankful for an answer!
    upload_2016-1-2_19-2-34.png
     
  2. jcsd
  3. Jan 2, 2016 #2
    The context is missing, but I'll guess that this is random walk?
    For a random walk process, what do you think is the average displacement?
    Another way to look at it would be to consider the [itex]\pm[/itex] signs - how many particles do you think will move in the + direction and how many in the - direction?
     
    Last edited: Jan 2, 2016
  4. Jan 2, 2016 #3
    Yeah, it is the random walk! :)
    Do you mean that the middle part equals zero (all negatives and positive deltas are on average 0) and that's why it can be canceled out?
    I thought it was some formula like (a+b)(a-b) where it's a²-ab+ab-b² where the inner parts just cancels out each other.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: What kind of formula is this and how is it to be retraced?
  1. What formula is this? (Replies: 1)

  2. What is this formula? (Replies: 5)

Loading...