function [leb_constant]=costante_lebesgue(pts)

rows_chebvand=length(pts);
V_pts =gallery('chebvand',rows_chebvand,pts);
M=max(5000,10*rows_chebvand);
pts_leb=linspace(-1,1,M); % PUNTI TEST.
V_leb = gallery('chebvand',rows_chebvand,pts_leb);
leb_constant=norm(V_pts\V_leb,1);