\\ b-adic representation of n
t_adic (n,b) = {my (q,r);
if (n<b,[n], [q,r]=[n\b,n%b];
concat(t_adic(q,b),[r]))}

\\ t_adic(n%b^k) filled with zeros
\\ to obtain k digits.
t_adicfull (n,b,k) = {my (v);
n=n%b^k; v=t_adic(n,b);
concat(vector(k-#v,i,0),v)}

\\ Ruffini-Horner.
t_ruffini (a,x) = {my (b=0); for (i=1,#a,b=b*x+a[i]); b}