def dmp_neg(f, u, K):
 if (not u):
  return dup_neg(f, K)
 v = (u - 1)
 return [dmp_neg(cf, v, K) for cf in f]

def dmp_neg ( f , u , K ) : if ( not u ) : return dup_neg ( f , K ) v = ( u - 1 ) return [ dmp_neg ( cf , v , K ) for cf in f ]
negate a polynomial in k[x] .