function poly3=poly_mul(poly1,poly2)
   N1=length(poly1)-1;
   N2=length(poly2)-1;
   poly3=zeros(N1+N2+1,1);
   for h=0:N1
       for k=0:N2
           poly3(h+k+1)=poly3(h+k+1)+poly1(h+1)*poly2(k+1);
       end;    
   end;