I need to compute the error, How to define the error between the exact and approximation.
--- y(x) = -y(x)
y(x) = exp(-x)
I have a problem in this code, my goal is to compute the error between the approximate solution obtained by RK3 and Exact and E ( approximation by RK3).
How to definie the error and prouve that the error is O(h^4) ( with one step) and the global error is O(h^3).
Thank you for helping me.