n=10;
>> p=Csebisev(n);x=sort(roots(p));
>> xx=-1:h/10:1;yy=abs(xx);pp=polyval(p,xx);
>> y=abs(x);
>> plot(x,y,'o',xx,yy,xx,pp);
>> n=100;
>> p=Csebisev(n);x=sort(roots(p));
>> xx=-1:h/10:1;yy=abs(xx);pp=polyval(p,xx);
>> y=abs(x);
>> plot(x,y,'o',xx,yy,xx,pp);
Warning: Imaginary parts of complex X and/or Y arguments ignored.
>> n=21;
>> p=Csebisev(n);x=sort(roots(p));
>> xx=-1:h/10:1;yy=abs(xx);pp=polyval(p,xx);
>> y=abs(x);
>> plot(x,y,'o',xx,yy,xx,pp);
>> 

function p=Csebisev(n)
    r=1;
    q=[1 0];
    for i=2:n;
            p=2*[q 0]-[0 0 r];
            r=q;
            q=p;
    end;