function z=polyadd(x,y)
% z=polyadd(x,y)
% for finding the coefficient vector for the sum
% of polynomials: x(s)=x(s)+y(s)

m=length(x); n=length(y);
if m>=n
   z=x+[zeros(1,m-n),y];
else
   z=y+[zeros(1,n-m),x];
end