Lagrange Interpolation limited to 13 (X,Y) Values ??

[nferry]

Hello,

I experienced a limitation using Lagrange interpolation,

I can only use a vector of max 13 values for correct interpolation,

this problem does not appear with nearest, linear, spline, or hermite cubic methods.

Best R.

Nicolas

[nferry]

Have you experienced the same problem ?

[nferry]

I tested the LV example:

labview\examples\analysis\intpxmpl.llb

In fact, there is the same problem with dataset 3 where there is greater than 13 control keys.

The curve has a strange behaviour with a huge peak that downscale all the others near a zero looking value.

This may be the mathematical law which is limited ?

Nicolas

[nferry · Accepted solution]

Ok I think I find the solutionon wikipedia Lagrange:

"Lagrange and other interpolation at equally spaced points, as in the example above, yield a polynomial oscillating above and below the true function. This behaviour tends to grow with the number of points, leading to a divergence known as Runge's phenomenon; the problem may be eliminated by choosing interpolation points at Chebyshev nodes."

Hope it helps you.

Nicolas