n=12;  % GRADO.
% NODI TEST.
s=-5:10/(10*n):5;  
% NODI EQSP.: ASCISSE/ORDINATE + INTP.TEST.
x=-5:10/n:5; y=runge(x);   
t=interpol(x,y,s);  
% NODI GCL.: ASCISSE/ORDINATE+INTP.TEST.
xgcl=cheb(-5,5,n+1); ygcl=runge(xgcl);
tt =interpol(xgcl, ygcl,s);  
% PLOT INTP. VS RUNGE.
plot(s,runge(s),s,t,s,tt);  
% ERRORI ASSOLUTI.
ee=norm(runge(s)-t,inf);ec=norm(runge(s)-tt,inf); 
fprintf('\n\t[ERR.][EQS]:%2.2e [GCL]:%2.2e',ee,ec);