I haven’t checked the formula recently, but I think that

a = (2x(i + 2) – x(i+1) -2x(i) -x(i-1) + 2x(i – 2)) / 14 is the least-square fit for the a_2 coefficient of x(i) = a_2 i^2 + a_1 i + a_0.

At the very least, if you have a quadratic of that form, the formula does return a_2.

]]>I use Tracker 4.11.0 and there the acceleration is calculated using the formula a = (2x (i + 2) -x (i-1) -2x (i) -x (i-1) + 2x (i + 1)) / 7t ^ 2. I could not find the justification for this formula and I want to consider acceleration according to the Stirling formula for the second derivative. Question: can I determine the algorithm for calculating the second derivative

]]>I’m sorry, I don’t understand your question.

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