Barycentric Lagrange Interpolating Polynomials and Lebesgue Constant

Computes lagrange interpolating polynomials and Lebesgue function/constant.

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The first script, barylag.m, performs a barycentric lagrange interpolation on a for a set of given data. This approach follows from a paper by L. N. Trefethen (ref inside script comments), and is much faster than the previous script. Additionally, it has been vectorized to improve computation time even more. The second script, lebesgue.m is for computing the lebesgue function and constant for a set of nodes. If you want to interpolate data using barylag but are using some unusual set of nodes, use the second script to check the lebesgue constant ensure good numerical conditioning.

Cite As

Greg von Winckel (2026). Barycentric Lagrange Interpolating Polynomials and Lebesgue Constant (https://uk.mathworks.com/matlabcentral/fileexchange/4478-barycentric-lagrange-interpolating-polynomials-and-lebesgue-constant), MATLAB Central File Exchange. Retrieved .

Acknowledgements

Inspired by: Lagrange polynomial interpolation

General Information

MATLAB Release Compatibility

  • Compatible with any release

Platform Compatibility

  • Windows
  • macOS
  • Linux
Version Published Release Notes Action
1.0.0.0

The script has been made into two scripts, a barycentric lagrange interpolation scheme which is much faster, and a lebesgue calculator for theoretical interest.