0
$\begingroup$

An interpolation function is unique. Also as far as i'm aware Lagrange interpolation gives the same polynomial as Newtons divided differences.

However when interpolating $\cos(x)$ at $x=\frac{-\pi}3;$ $0;$ $\frac\pi3$

Lagrange's gives $\frac{(-9x^2)}{(2\pi^2)}+1$

Newtons Gives $1-(\frac{3x}{2\pi})$

Are any of my initial assumptions wrong?

Could somebody explain this to me please?

  • 0
    No, iterpolation functions aren't unique. But there is only one n-degree polynom if you interpolate n+1 values. – 2017-01-08
  • 0
    You should go one step further in your divided difference so as to include your third point (-pi/3 if I am correct). – 2017-01-08

0 Answers 0