2.
At first, we sample
in the
(
is odd) equidistant points around
:
![Rendered by QuickLaTeX.com \[ f_k = f(x_k),\: x_k = x^*+kh,\: k=-\frac{N-1}{2},\dots,\frac{N-1}{2} \]](https://bachillerato.reformamatematica.net/wp-content/ql-cache/quicklatex.com-458dd0629c012e844415561aa94a364a_l3.png)
where

is some step.
Then we interpolate points

by polynomial
(1) 
Its coefficients

are found as a solution of system of linear equations:
(2) 
Here are references to existing equations: (
1), (
2).
Here is reference to non-existing equation (??).