I need help on matlab. Someone help me please.
Given a function f(x) and a vector $x=x_0,x_1,x_2,...x_N)$ output a vector of approximations for f'(x) at $x_0,x_1,...,x_{N-1}$ using the difference quotient

Question

I need help on matlab. Someone help me please. 
Given a function f(x) and a vector $x=x_0,x_1,x_2,...x_N)$ output a vector of approximations for  f'(x) at $x_0,x_1,...,x_{N-1}$ using the difference quotient

parthkohli · Answer

Am I understanding the problem well? Suppose your vector is sorted.$$f'(x_k) \approx \frac{1}2 \left(\frac{f(x_k) - f(x_{k-1})}{x_k - x_{k-1}} + \frac{f(x_{k+1})-f(x_{k})}{x_{k+1 }-x_{k}} \right)$$This works, but for better accuracy, use weighted means. It should be weighted more towards the place where the difference is less.

loser66 · Answer

I need create a function on matlab with those condition but I don't know why I can't run it. Can you please help me step by step?

parthkohli · Answer

I can help you with the math, but not MATLAB. :(

loser66 · Answer

Like 
step1: click on "new " and choose "function"
step2: create the name of function
step3: Save it on matlab document
step4:...
I screw it up any time I work on matlab. :(