l = bound2poly(lower, dim, nvar, -1);
pos = isl_qpolynomial_terms_of_sign(data->poly, data->signs, sign);
neg = isl_qpolynomial_terms_of_sign(data->poly, data->signs, -sign);
l = bound2poly(lower, dim, nvar, -1);
pos = isl_qpolynomial_terms_of_sign(data->poly, data->signs, sign);
neg = isl_qpolynomial_terms_of_sign(data->poly, data->signs, -sign);