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

def dmp_abs ( f , u , K ) : if ( not u ) : return dup_abs ( f , K ) v = ( u - 1 ) return [ dmp_abs ( cf , v , K ) for cf in f ]
make all coefficients positive in k[x] .