def dmp_l1_norm(f, u, K):
 if (not u):
  return dup_l1_norm(f, K)
 v = (u - 1)
 return sum([dmp_l1_norm(c, v, K) for c in f])

def dmp_l1_norm ( f , u , K ) : if ( not u ) : return dup_l1_norm ( f , K ) v = ( u - 1 ) return sum ( [ dmp_l1_norm ( c , v , K ) for c in f ] )
returns l1 norm of a polynomial in k[x] .