def dup_zz_hensel_lift(p, f, f_list, l, K): """ Multifactor Hensel lifting in `Z[x]`. Given a prime `p`, polynomial `f` over `Z[x]` such that `lc(f)` is a unit modulo `p`, monic pair-wise coprime polynomials `f_i` over `Z[x]` satisfying:: f = lc(f) f_1 ... f_r (mod p) and a positive integer `l`, returns a list of monic polynomials `F_1`, `F_2`, ..., `F_r` satisfying:: f = lc(f) F_1 ... F_r (mod p**l) F_i = f_i (mod p), i = 1..r References ========== 1. [Gathen99]_ """ r = len(f_list) lc = dup_LC(f, K) if r == 1: F = dup_mul_ground(f, K.gcdex(lc, p**l)[0], K) return [ dup_trunc(F, p**l, K) ] m = p k = r // 2 d = int(_ceil(_log(l, 2))) g = gf_from_int_poly([lc], p) for f_i in f_list[:k]: g = gf_mul(g, gf_from_int_poly(f_i, p), p, K) h = gf_from_int_poly(f_list[k], p) for f_i in f_list[k + 1:]: h = gf_mul(h, gf_from_int_poly(f_i, p), p, K) s, t, _ = gf_gcdex(g, h, p, K) g = gf_to_int_poly(g, p) h = gf_to_int_poly(h, p) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) for _ in range(1, d + 1): (g, h, s, t), m = dup_zz_hensel_step(m, f, g, h, s, t, K), m**2 return dup_zz_hensel_lift(p, g, f_list[:k], l, K) \ + dup_zz_hensel_lift(p, h, f_list[k:], l, K)
def dup_zz_hensel_lift(p, f, f_list, l, K): """ Multifactor Hensel lifting in `Z[x]`. Given a prime `p`, polynomial `f` over `Z[x]` such that `lc(f)` is a unit modulo `p`, monic pair-wise coprime polynomials `f_i` over `Z[x]` satisfying:: f = lc(f) f_1 ... f_r (mod p) and a positive integer `l`, returns a list of monic polynomials `F_1`, `F_2`, ..., `F_r` satisfying:: f = lc(f) F_1 ... F_r (mod p**l) F_i = f_i (mod p), i = 1..r References ========== 1. [Gathen99]_ """ r = len(f_list) lc = dup_LC(f, K) if r == 1: F = dup_mul_ground(f, K.gcdex(lc, p**l)[0], K) return [dup_trunc(F, p**l, K)] m = p k = r // 2 d = int(_ceil(_log(l, 2))) g = gf_from_int_poly([lc], p) for f_i in f_list[:k]: g = gf_mul(g, gf_from_int_poly(f_i, p), p, K) h = gf_from_int_poly(f_list[k], p) for f_i in f_list[k + 1:]: h = gf_mul(h, gf_from_int_poly(f_i, p), p, K) s, t, _ = gf_gcdex(g, h, p, K) g = gf_to_int_poly(g, p) h = gf_to_int_poly(h, p) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) for _ in range(1, d + 1): (g, h, s, t), m = dup_zz_hensel_step(m, f, g, h, s, t, K), m**2 return dup_zz_hensel_lift(p, g, f_list[:k], l, K) \ + dup_zz_hensel_lift(p, h, f_list[k:], l, K)
def test_gf_berlekamp(): f = gf_from_int_poly([1, -3, 1, -3, -1, -3, 1], 11) Q = [[1, 0, 0, 0, 0, 0], [3, 5, 8, 8, 6, 5], [3, 6, 6, 1, 10, 0], [9, 4, 10, 3, 7, 9], [7, 8, 10, 0, 0, 8], [8, 10, 7, 8, 10, 8]] V = [[1, 0, 0, 0, 0, 0], [0, 1, 1, 1, 1, 0], [0, 0, 7, 9, 0, 1]] assert gf_Qmatrix(f, 11, ZZ) == Q assert gf_Qbasis(Q, 11, ZZ) == V assert gf_berlekamp(f, 11, ZZ) == \ [[1, 1], [1, 5, 3], [1, 2, 3, 4]] f = [1, 0, 1, 0, 10, 10, 8, 2, 8] Q = [[1, 0, 0, 0, 0, 0, 0, 0], [2, 1, 7, 11, 10, 12, 5, 11], [3, 6, 4, 3, 0, 4, 7, 2], [4, 3, 6, 5, 1, 6, 2, 3], [2, 11, 8, 8, 3, 1, 3, 11], [6, 11, 8, 6, 2, 7, 10, 9], [5, 11, 7, 10, 0, 11, 7, 12], [3, 3, 12, 5, 0, 11, 9, 12]] V = [[1, 0, 0, 0, 0, 0, 0, 0], [0, 5, 5, 0, 9, 5, 1, 0], [0, 9, 11, 9, 10, 12, 0, 1]] assert gf_Qmatrix(f, 13, ZZ) == Q assert gf_Qbasis(Q, 13, ZZ) == V assert gf_berlekamp(f, 13, ZZ) == \ [[1, 3], [1, 8, 4, 12], [1, 2, 3, 4, 6]]
def dup_zz_diophantine(F, m, p, K): """Wang/EEZ: Solve univariate Diophantine equations. """ if len(F) == 2: a, b = F f = gf_from_int_poly(a, p) g = gf_from_int_poly(b, p) s, t, G = gf_gcdex(g, f, p, K) s = gf_lshift(s, m, K) t = gf_lshift(t, m, K) q, s = gf_div(s, f, p, K) t = gf_add_mul(t, q, g, p, K) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) result = [s, t] else: G = [F[-1]] for f in reversed(F[1:-1]): G.insert(0, dup_mul(f, G[0], K)) S, T = [], [[1]] for f, g in zip(F, G): t, s = dmp_zz_diophantine([g, f], T[-1], [], 0, p, 1, K) T.append(t) S.append(s) result, S = [], S + [T[-1]] for s, f in zip(S, F): s = gf_from_int_poly(s, p) f = gf_from_int_poly(f, p) r = gf_rem(gf_lshift(s, m, K), f, p, K) s = gf_to_int_poly(r, p) result.append(s) return result
def applyModulus(self): coeffs = gf_from_int_poly( self.coeffs[::-1], self.p )[:: -1] # Yep, reversing the list twice is faster than applying the modulus manually #print "after:", self.coeffs for i in range(len(coeffs))[::-1]: if coeffs[i] != 0: self.coeffs = coeffs[:i + 1] return #self.coeffs = [self.coeffs[0]] # In this case, we don't care if c[0] == 0, we need at least one element. if len(coeffs) == 0: self.coeffs = [0]
def test_gf_berlekamp(): f = gf_from_int_poly([1,-3,1,-3,-1,-3,1], 11) Q = [[1, 0, 0, 0, 0, 0], [3, 5, 8, 8, 6, 5], [3, 6, 6, 1,10, 0], [9, 4,10, 3, 7, 9], [7, 8,10, 0, 0, 8], [8,10, 7, 8,10, 8]] V = [[1, 0, 0, 0, 0, 0], [0, 1, 1, 1, 1, 0], [0, 0, 7, 9, 0, 1]] assert gf_Qmatrix(f, 11, ZZ) == Q assert gf_Qbasis(Q, 11, ZZ) == V assert gf_berlekamp(f, 11, ZZ) == \ [[1, 1], [1, 5, 3], [1, 2, 3, 4]] f = [1,0,1,0,10,10,8,2,8] Q = [[1, 0, 0, 0, 0, 0, 0, 0], [2, 1, 7,11,10,12, 5,11], [3, 6, 4, 3, 0, 4, 7, 2], [4, 3, 6, 5, 1, 6, 2, 3], [2,11, 8, 8, 3, 1, 3,11], [6,11, 8, 6, 2, 7,10, 9], [5,11, 7,10, 0,11, 7,12], [3, 3,12, 5, 0,11, 9,12]] V = [[1, 0, 0, 0, 0, 0, 0, 0], [0, 5, 5, 0, 9, 5, 1, 0], [0, 9,11, 9,10,12, 0, 1]] assert gf_Qmatrix(f, 13, ZZ) == Q assert gf_Qbasis(Q, 13, ZZ) == V assert gf_berlekamp(f, 13, ZZ) == \ [[1, 3], [1, 8, 4, 12], [1, 2, 3, 4, 6]]
def dup_zz_zassenhaus(f, K): """Factor primitive square-free polynomials in `Z[x]`. """ n = dup_degree(f) if n == 1: return [f] A = dup_max_norm(f, K) b = dup_LC(f, K) B = int(abs(K.sqrt(K(n + 1)) * 2**n * A * b)) C = int((n + 1)**(2 * n) * A**(2 * n - 1)) gamma = int(_ceil(2 * _log(C, 2))) bound = int(2 * gamma * _log(gamma)) for p in xrange(3, bound + 1): if not isprime(p) or b % p == 0: continue p = K.convert(p) F = gf_from_int_poly(f, p) if gf_sqf_p(F, p, K): break l = int(_ceil(_log(2 * B + 1, p))) modular = [] for ff in gf_factor_sqf(F, p, K)[1]: modular.append(gf_to_int_poly(ff, p)) g = dup_zz_hensel_lift(p, f, modular, l, K) T = set(range(len(g))) factors, s = [], 1 while 2 * s <= len(T): for S in subsets(T, s): G, H = [b], [b] S = set(S) for i in S: G = dup_mul(G, g[i], K) for i in T - S: H = dup_mul(H, g[i], K) G = dup_trunc(G, p**l, K) H = dup_trunc(H, p**l, K) G_norm = dup_l1_norm(G, K) H_norm = dup_l1_norm(H, K) if G_norm * H_norm <= B: T = T - S G = dup_primitive(G, K)[1] f = dup_primitive(H, K)[1] factors.append(G) b = dup_LC(f, K) break else: s += 1 return factors + [f]
def dup_zz_zassenhaus(f, K): """Factor primitive square-free polynomials in `Z[x]`. """ n = dup_degree(f) if n == 1: return [f] fc = f[-1] A = dup_max_norm(f, K) b = dup_LC(f, K) B = int(abs(K.sqrt(K(n + 1)) * 2**n * A * b)) C = int((n + 1)**(2 * n) * A**(2 * n - 1)) gamma = int(_ceil(2 * _log(C, 2))) bound = int(2 * gamma * _log(gamma)) a = [] # choose a prime number `p` such that `f` be square free in Z_p # if there are many factors in Z_p, choose among a few different `p` # the one with fewer factors for px in xrange(3, bound + 1): if not isprime(px) or b % px == 0: continue px = K.convert(px) F = gf_from_int_poly(f, px) if not gf_sqf_p(F, px, K): continue fsqfx = gf_factor_sqf(F, px, K)[1] a.append((px, fsqfx)) if len(fsqfx) < 15 or len(a) > 4: break p, fsqf = min(a, key=lambda x: len(x[1])) l = int(_ceil(_log(2 * B + 1, p))) modular = [gf_to_int_poly(ff, p) for ff in fsqf] g = dup_zz_hensel_lift(p, f, modular, l, K) sorted_T = range(len(g)) T = set(sorted_T) factors, s = [], 1 pl = p**l while 2 * s <= len(T): for S in subsets(sorted_T, s): # lift the constant coefficient of the product `G` of the factors # in the subset `S`; if it is does not divide `fc`, `G` does # not divide the input polynomial if b == 1: q = 1 for i in S: q = q * g[i][-1] q = q % pl if not _test_pl(fc, q, pl): continue else: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) G1 = dup_primitive(G, K)[1] q = G1[-1] if q and fc % q != 0: continue H = [b] S = set(S) T_S = T - S if b == 1: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) for i in T_S: H = dup_mul(H, g[i], K) H = dup_trunc(H, pl, K) G_norm = dup_l1_norm(G, K) H_norm = dup_l1_norm(H, K) if G_norm * H_norm <= B: T = T_S sorted_T = [i for i in sorted_T if i not in S] G = dup_primitive(G, K)[1] f = dup_primitive(H, K)[1] factors.append(G) b = dup_LC(f, K) break else: s += 1 return factors + [f]
def dup_zz_zassenhaus(f, K): """Factor primitive square-free polynomials in `Z[x]`. """ n = dup_degree(f) if n == 1: return [f] A = dup_max_norm(f, K) b = dup_LC(f, K) B = int(abs(K.sqrt(K(n+1))*2**n*A*b)) C = int((n+1)**(2*n)*A**(2*n-1)) gamma = int(ceil(2*log(C, 2))) bound = int(2*gamma*log(gamma)) for p in xrange(3, bound+1): if not isprime(p) or b % p == 0: continue p = K.convert(p) F = gf_from_int_poly(f, p) if gf_sqf_p(F, p, K): break l = int(ceil(log(2*B + 1, p))) modular = [] for ff in gf_factor_sqf(F, p, K)[1]: modular.append(gf_to_int_poly(ff, p)) g = dup_zz_hensel_lift(p, f, modular, l, K) T = set(range(len(g))) factors, s = [], 1 while 2*s <= len(T): for S in subsets(T, s): G, H = [b], [b] S = set(S) for i in S: G = dup_mul(G, g[i], K) for i in T-S: H = dup_mul(H, g[i], K) G = dup_trunc(G, p**l, K) H = dup_trunc(H, p**l, K) G_norm = dup_l1_norm(G, K) H_norm = dup_l1_norm(H, K) if G_norm*H_norm <= B: T = T - S G = dup_primitive(G, K)[1] f = dup_primitive(H, K)[1] factors.append(G) b = dup_LC(f, K) break else: s += 1 return factors + [f]
def test_gf_factor(): assert gf_factor([], 11, ZZ) == (0, []) assert gf_factor([1], 11, ZZ) == (1, []) assert gf_factor([1,1], 11, ZZ) == (1, [([1, 1], 1)]) assert gf_factor_sqf([], 11, ZZ) == (0, []) assert gf_factor_sqf([1], 11, ZZ) == (1, []) assert gf_factor_sqf([1,1], 11, ZZ) == (1, [[1, 1]]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor_sqf([], 11, ZZ) == (0, []) assert gf_factor_sqf([1], 11, ZZ) == (1, []) assert gf_factor_sqf([1,1], 11, ZZ) == (1, [[1, 1]]) config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor_sqf([], 11, ZZ) == (0, []) assert gf_factor_sqf([1], 11, ZZ) == (1, []) assert gf_factor_sqf([1,1], 11, ZZ) == (1, [[1, 1]]) config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor_sqf([], 11, ZZ) == (0, []) assert gf_factor_sqf([1], 11, ZZ) == (1, []) assert gf_factor_sqf([1,1], 11, ZZ) == (1, [[1, 1]]) f, p = [1,0,0,1,0], 2 g = (1, [([1, 0], 1), ([1, 1], 1), ([1, 1, 1], 1)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g g = (1, [[1, 0], [1, 1], [1, 1, 1]]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor_sqf(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor_sqf(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor_sqf(f, p, ZZ) == g f, p = gf_from_int_poly([1,-3,1,-3,-1,-3,1], 11), 11 g = (1, [([1, 1], 1), ([1, 5, 3], 1), ([1, 2, 3, 4], 1)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g f, p = [1, 5, 8, 4], 11 g = (1, [([1, 1], 1), ([1, 2], 2)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g f, p = [1, 1, 10, 1, 0, 10, 10, 10, 0, 0], 11 g = (1, [([1, 0], 2), ([1, 9, 5], 1), ([1, 3, 0, 8, 5, 2], 1)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g f, p = gf_from_dict({32: 1, 0: 1}, 11, ZZ), 11 g = (1, [([1, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 10], 1), ([1, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 10], 1)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g f, p = gf_from_dict({32: 8, 0: 5}, 11, ZZ), 11 g = (8, [([1, 3], 1), ([1, 8], 1), ([1, 0, 9], 1), ([1, 2, 2], 1), ([1, 9, 2], 1), ([1, 0, 5, 0, 7], 1), ([1, 0, 6, 0, 7], 1), ([1, 0, 0, 0, 1, 0, 0, 0, 6], 1), ([1, 0, 0, 0, 10, 0, 0, 0, 6], 1)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g f, p = gf_from_dict({63: 8, 0: 5}, 11, ZZ), 11 g = (8, [([1, 7], 1), ([1, 4, 5], 1), ([1, 6, 8, 2], 1), ([1, 9, 9, 2], 1), ([1, 0, 0, 9, 0, 0, 4], 1), ([1, 2, 0, 8, 4, 6, 4], 1), ([1, 2, 3, 8, 0, 6, 4], 1), ([1, 2, 6, 0, 8, 4, 4], 1), ([1, 3, 3, 1, 6, 8, 4], 1), ([1, 5, 6, 0, 8, 6, 4], 1), ([1, 6, 2, 7, 9, 8, 4], 1), ([1, 10, 4, 7, 10, 7, 4], 1), ([1, 10, 10, 1, 4, 9, 4], 1)]) config.setup('GF_FACTOR_METHOD', 'berlekamp') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g # Gathen polynomials: x**n + x + 1 (mod p > 2**n * pi) p = ZZ(nextprime(int((2**15 * pi).evalf()))) f = gf_from_dict({15: 1, 1: 1, 0: 1}, p, ZZ) assert gf_sqf_p(f, p, ZZ) == True g = (1, [([1, 22730, 68144], 1), ([1, 81553, 77449, 86810, 4724], 1), ([1, 86276, 56779, 14859, 31575], 1), ([1, 15347, 95022, 84569, 94508, 92335], 1)]) config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g g = (1, [[1, 22730, 68144], [1, 81553, 77449, 86810, 4724], [1, 86276, 56779, 14859, 31575], [1, 15347, 95022, 84569, 94508, 92335]]) config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor_sqf(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor_sqf(f, p, ZZ) == g # Shoup polynomials: f = a_0 x**n + a_1 x**(n-1) + ... + a_n # (mod p > 2**(n-2) * pi), where a_n = a_{n-1}**2 + 1, a_0 = 1 p = ZZ(nextprime(int((2**4 * pi).evalf()))) f = [1, 2, 5, 26, 41, 39, 38] assert gf_sqf_p(f, p, ZZ) == True g = (1, [([1, 44, 26], 1), ([1, 11, 25, 18, 30], 1)]) config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor(f, p, ZZ) == g g = (1, [[1, 44, 26], [1, 11, 25, 18, 30]]) config.setup('GF_FACTOR_METHOD', 'zassenhaus') assert gf_factor_sqf(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'shoup') assert gf_factor_sqf(f, p, ZZ) == g config.setup('GF_FACTOR_METHOD', 'other') raises(KeyError, lambda: gf_factor([1,1], 11, ZZ)) config.setup('GF_FACTOR_METHOD')
def test_gf_from_to_int_poly(): assert gf_from_int_poly([1,0,7,2,20], 5) == [1,0,2,2,0] assert gf_to_int_poly([1,0,4,2,3], 5) == [1,0,-1,2,-2] assert gf_to_int_poly([10], 11, symmetric=True) == [-1] assert gf_to_int_poly([10], 11, symmetric=False) == [10]
def dup_zz_zassenhaus(f, K): """Factor primitive square-free polynomials in `Z[x]`. """ n = dup_degree(f) if n == 1: return [f] fc = f[-1] A = dup_max_norm(f, K) b = dup_LC(f, K) B = int(abs(K.sqrt(K(n + 1))*2**n*A*b)) C = int((n + 1)**(2*n)*A**(2*n - 1)) gamma = int(_ceil(2*_log(C, 2))) bound = int(2*gamma*_log(gamma)) a = [] # choose a prime number `p` such that `f` be square free in Z_p # if there are many factors in Z_p, choose among a few different `p` # the one with fewer factors for px in range(3, bound + 1): if not isprime(px) or b % px == 0: continue px = K.convert(px) F = gf_from_int_poly(f, px) if not gf_sqf_p(F, px, K): continue fsqfx = gf_factor_sqf(F, px, K)[1] a.append((px, fsqfx)) if len(fsqfx) < 15 or len(a) > 4: break p, fsqf = min(a, key=lambda x: len(x[1])) l = int(_ceil(_log(2*B + 1, p))) modular = [gf_to_int_poly(ff, p) for ff in fsqf] g = dup_zz_hensel_lift(p, f, modular, l, K) sorted_T = range(len(g)) T = set(sorted_T) factors, s = [], 1 pl = p**l while 2*s <= len(T): for S in subsets(sorted_T, s): # lift the constant coefficient of the product `G` of the factors # in the subset `S`; if it is does not divide `fc`, `G` does # not divide the input polynomial if b == 1: q = 1 for i in S: q = q*g[i][-1] q = q % pl if not _test_pl(fc, q, pl): continue else: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) G = dup_primitive(G, K)[1] q = G[-1] if q and fc % q != 0: continue H = [b] S = set(S) T_S = T - S if b == 1: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) for i in T_S: H = dup_mul(H, g[i], K) H = dup_trunc(H, pl, K) G_norm = dup_l1_norm(G, K) H_norm = dup_l1_norm(H, K) if G_norm*H_norm <= B: T = T_S sorted_T = [i for i in sorted_T if i not in S] G = dup_primitive(G, K)[1] f = dup_primitive(H, K)[1] factors.append(G) b = dup_LC(f, K) break else: s += 1 return factors + [f]