Lagrange and newton poly

I can't build lagrangepoly and newtonpoly using "spline" X = [0.13 0.18 0.23 0.28 0.33 0.38]; Y = [0.129 0.179 0.228 0.276 0.324 0.371]; Please help me.

Answer 1

[Laura Proctor]

You can try this function from the file exchange: http://www.mathworks.com/matlabcentral/fileexchange/13151-lagrange-interpolator-polynomial

[Anatoliy]

But I don't know that in an example means [P,R,S]????

[Laura Proctor]

From the description:

P [returns] the N coefficients defining that polynomial.

R returns the x co-ordinates of the N-1 extrema/inflection points of the resulting polynomial (roots of its derivative)

S returns the value of the polynomial at those points