refine the grid with 2^refine grid points;
can only be an integer between 2 and 10, default 4.
plotting
shall the Lebesgue function be plotted.
Value
Lebesgue constant for the given grid points.
Details
The Lebesgue constant gives an estimation $||P_n f|| \le L ||f||$
(in minimax norm) where $P_n f$ is the interpolating polynomial of
order $n$ for $f$ on an interval $[a, b]$.
References
Berrut, J.-P., and L. Nick Trefethen (2004). ``Barycentric Lagrange
Interpolation''. SIAM Review, Vol. 46(3), pp.501--517.