def dmp_sub(f, g, u, K):
"""Subtract dense polynomials in `K[X]`. """
if not u:
return dup_sub(f, g, K)
df = dmp_degree(f, u)
if df < 0:
return dmp_neg(g, u, K)
dg = dmp_degree(g, u)
if dg < 0:
return f
v = u-1
if df == dg:
return dmp_strip([ dmp_sub(a, b, v, K) for a, b in zip(f, g) ], u)
else:
k = abs(df - dg)
if df > dg:
h, f = f[:k], f[k:]
else:
h, g = dmp_neg(g[:k], u, K), g[k:]
return h + [ dmp_sub(a, b, v, K) for a, b in zip(f, g) ]
def _dmp_simplify_gcd(f, g, u, K):
"""Try to eliminate ``x_0`` from GCD computation in ``K[X]``. """
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if df > 0 and dg > 0:
return None
if not (df or dg):
F = dmp_LC(f, K)
G = dmp_LC(g, K)
else:
if not df:
F = dmp_LC(f, K)
G = dmp_content(g, u, K)
else:
F = dmp_content(f, u, K)
G = dmp_LC(g, K)
v = u - 1
h = dmp_gcd(F, G, v, K)
cff = [ dmp_exquo(cf, h, v, K) for cf in f ]
cfg = [ dmp_exquo(cg, h, v, K) for cg in g ]
return [h], cff, cfg
def dmp_prem(f, g, u, K):
"""Polynomial pseudo-remainder in `K[X]`. """
if not u:
return dup_prem(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
r = f
if df < dg:
return r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
j, N = dr-dg, N-1
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
c = dmp_pow(lc_g, N, u-1, K)
return dmp_mul_term(r, c, 0, u, K)
def dmp_mul(f, g, u, K):
"""Multiply dense polynomials in `K[X]`. """
if not u:
return dup_mul(f, g, K)
if f == g:
return dmp_sqr(f, u, K)
df = dmp_degree(f, u)
if df < 0:
return f
dg = dmp_degree(g, u)
if dg < 0:
return g
h, v = [], u-1
for i in xrange(0, df+dg+1):
coeff = dmp_zero(v)
for j in xrange(max(0, i-dg), min(df, i)+1):
coeff = dmp_add(coeff, dmp_mul(f[j], g[i-j], v, K), v, K)
h.append(coeff)
return h
def dmp_sqf_list(f, u, K, all=False):
"""
Return square-free decomposition of a polynomial in ``K[X]``.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.sqfreetools import dmp_sqf_list
>>> f = ZZ.map([[1], [2, 0], [1, 0, 0], [], [], []])
>>> dmp_sqf_list(f, 1, ZZ)
(1, [([[1], [1, 0]], 2), ([[1], []], 3)])
>>> dmp_sqf_list(f, 1, ZZ, all=True)
(1, [([[1]], 1), ([[1], [1, 0]], 2), ([[1], []], 3)])
"""
if not u:
return dup_sqf_list(f, K, all=all)
if not K.has_CharacteristicZero:
return dmp_gf_sqf_list(f, u, K, all=all)
if K.has_Field or not K.is_Exact:
coeff = dmp_ground_LC(f, u, K)
f = dmp_ground_monic(f, u, K)
else:
coeff, f = dmp_ground_primitive(f, u, K)
if K.is_negative(dmp_ground_LC(f, u, K)):
f = dmp_neg(f, u, K)
coeff = -coeff
if dmp_degree(f, u) <= 0:
return coeff, []
result, i = [], 1
h = dmp_diff(f, 1, u, K)
g, p, q = dmp_inner_gcd(f, h, u, K)
while True:
d = dmp_diff(p, 1, u, K)
h = dmp_sub(q, d, u, K)
if dmp_zero_p(h, u):
result.append((p, i))
break
g, p, q = dmp_inner_gcd(p, h, u, K)
if all or dmp_degree(g, u) > 0:
result.append((g, i))
i += 1
return coeff, result
def dmp_sqf_list(f, u, K, all=False):
"""
Return square-free decomposition of a polynomial in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = x**5 + 2*x**4*y + x**3*y**2
>>> R.dmp_sqf_list(f)
(1, [(x + y, 2), (x, 3)])
>>> R.dmp_sqf_list(f, all=True)
(1, [(1, 1), (x + y, 2), (x, 3)])
"""
if not u:
return dup_sqf_list(f, K, all=all)
if K.is_FiniteField:
return dmp_gf_sqf_list(f, u, K, all=all)
if K.has_Field:
coeff = dmp_ground_LC(f, u, K)
f = dmp_ground_monic(f, u, K)
else:
coeff, f = dmp_ground_primitive(f, u, K)
if K.is_negative(dmp_ground_LC(f, u, K)):
f = dmp_neg(f, u, K)
coeff = -coeff
if dmp_degree(f, u) <= 0:
return coeff, []
result, i = [], 1
h = dmp_diff(f, 1, u, K)
g, p, q = dmp_inner_gcd(f, h, u, K)
while True:
d = dmp_diff(p, 1, u, K)
h = dmp_sub(q, d, u, K)
if dmp_zero_p(h, u):
result.append((p, i))
break
g, p, q = dmp_inner_gcd(p, h, u, K)
if all or dmp_degree(g, u) > 0:
result.append((g, i))
i += 1
return coeff, result
def dmp_zz_collins_resultant(f, g, u, K):
"""
Collins's modular resultant algorithm in `Z[X]`.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = x + y + 2
>>> g = 2*x*y + x + 3
>>> R.dmp_zz_collins_resultant(f, g)
-2*y**2 - 5*y + 1
"""
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < 0 or m < 0:
return dmp_zero(u - 1)
A = dmp_max_norm(f, u, K)
B = dmp_max_norm(g, u, K)
a = dmp_ground_LC(f, u, K)
b = dmp_ground_LC(g, u, K)
v = u - 1
B = K(2)*K.factorial(K(n + m))*A**m*B**n
r, p, P = dmp_zero(v), K.one, K.one
while P <= B:
p = K(nextprime(p))
while not (a % p) or not (b % p):
p = K(nextprime(p))
F = dmp_ground_trunc(f, p, u, K)
G = dmp_ground_trunc(g, p, u, K)
try:
R = dmp_zz_modular_resultant(F, G, p, u, K)
except HomomorphismFailed:
continue
if K.is_one(P):
r = R
else:
r = dmp_apply_pairs(r, R, _collins_crt, (P, p, K), v, K)
P *= p
return r
def dmp_zz_collins_resultant(f, g, u, K):
"""
Collins's modular resultant algorithm in `Z[X]`.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.euclidtools import dmp_zz_collins_resultant
>>> f = ZZ.map([[1], [1, 2]])
>>> g = ZZ.map([[2, 1], [3]])
>>> dmp_zz_collins_resultant(f, g, 1, ZZ)
[-2, -5, 1]
"""
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < 0 or m < 0:
return dmp_zero(u-1)
A = dmp_max_norm(f, u, K)
B = dmp_max_norm(g, u, K)
a = dmp_ground_LC(f, u, K)
b = dmp_ground_LC(g, u, K)
v = u - 1
B = K(2)*K.factorial(n+m)*A**m*B**n
r, p, P = dmp_zero(v), K.one, K.one
while P <= B:
p = K(nextprime(p))
while not (a % p) or not (b % p):
p = K(nextprime(p))
F = dmp_ground_trunc(f, p, u, K)
G = dmp_ground_trunc(g, p, u, K)
try:
R = dmp_zz_modular_resultant(F, G, p, u, K)
except HomomorphismFailed:
continue
if K.is_one(P):
r = R
else:
r = dmp_apply_pairs(r, R, _collins_crt, (P, p, K), v, K)
P *= p
return r
def dmp_pdiv(f, g, u, K):
"""
Polynomial pseudo-division in ``K[X]``.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densearith import dmp_pdiv
>>> f = ZZ.map([[1], [1, 0], []])
>>> g = ZZ.map([[2], [2]])
>>> dmp_pdiv(f, g, 1, ZZ)
([[2], [2, -2]], [[-4, 4]])
"""
if not u:
return dup_pdiv(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r = dmp_zero(u), f
if df < dg:
return q, r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
j, N = dr-dg, N-1
Q = dmp_mul_term(q, lc_g, 0, u, K)
q = dmp_add_term(Q, lc_r, j, u, K)
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
c = dmp_pow(lc_g, N, u-1, K)
q = dmp_mul_term(q, c, 0, u, K)
r = dmp_mul_term(r, c, 0, u, K)
return q, r
def dmp_pdiv(f, g, u, K):
"""
Polynomial pseudo-division in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_pdiv(x**2 + x*y, 2*x + 2)
(2*x + 2*y - 2, -4*y + 4)
"""
if not u:
return dup_pdiv(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r, dr = dmp_zero(u), f, df
if df < dg:
return q, r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
lc_r = dmp_LC(r, K)
j, N = dr - dg, N - 1
Q = dmp_mul_term(q, lc_g, 0, u, K)
q = dmp_add_term(Q, lc_r, j, u, K)
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
_dr, dr = dr, dmp_degree(r, u)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
c = dmp_pow(lc_g, N, u - 1, K)
q = dmp_mul_term(q, c, 0, u, K)
r = dmp_mul_term(r, c, 0, u, K)
return q, r
def dmp_ff_div(f, g, u, K):
"""
Polynomial division with remainder over a field.
Examples
========
>>> from sympy.polys.domains import QQ
>>> from sympy.polys.densearith import dmp_ff_div
>>> f = QQ.map([[1], [1, 0], []])
>>> g = QQ.map([[2], [2]])
>>> dmp_ff_div(f, g, 1, QQ)
([[1/2], [1/2, -1/2]], [[-1/1, 1/1]])
"""
if not u:
return dup_ff_div(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r = dmp_zero(u), f
if df < dg:
return q, r
lc_g, v = dmp_LC(g, K), u-1
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
c, R = dmp_ff_div(lc_r, lc_g, v, K)
if not dmp_zero_p(R, v):
break
j = dr - dg
q = dmp_add_term(q, c, j, u, K)
h = dmp_mul_term(g, c, j, u, K)
r = dmp_sub(r, h, u, K)
return q, r
def dmp_rr_div(f, g, u, K):
"""
Multivariate division with remainder over a ring.
**Examples**
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densearith import dmp_rr_div
>>> f = ZZ.map([[1], [1, 0], []])
>>> g = ZZ.map([[2], [2]])
>>> dmp_rr_div(f, g, 1, ZZ)
([[]], [[1], [1, 0], []])
"""
if not u:
return dup_rr_div(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r = dmp_zero(u), f
if df < dg:
return q, r
lc_g, v = dmp_LC(g, K), u-1
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
c, R = dmp_rr_div(lc_r, lc_g, v, K)
if not dmp_zero_p(R, v):
break
j = dr - dg
q = dmp_add_term(q, c, j, u, K)
h = dmp_mul_term(g, c, j, u, K)
r = dmp_sub(r, h, u, K)
return q, r
def dmp_ff_div(f, g, u, K):
"""
Polynomial division with remainder over a field.
Examples
========
>>> from sympy.polys import ring, QQ
>>> R, x,y = ring("x,y", QQ)
>>> R.dmp_ff_div(x**2 + x*y, 2*x + 2)
(1/2*x + 1/2*y - 1/2, -y + 1)
"""
if not u:
return dup_ff_div(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r, dr = dmp_zero(u), f, df
if df < dg:
return q, r
lc_g, v = dmp_LC(g, K), u - 1
while True:
lc_r = dmp_LC(r, K)
c, R = dmp_ff_div(lc_r, lc_g, v, K)
if not dmp_zero_p(R, v):
break
j = dr - dg
q = dmp_add_term(q, c, j, u, K)
h = dmp_mul_term(g, c, j, u, K)
r = dmp_sub(r, h, u, K)
_dr, dr = dr, dmp_degree(r, u)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
return q, r
def dmp_rr_div(f, g, u, K):
"""
Multivariate division with remainder over a ring.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_rr_div(x**2 + x*y, 2*x + 2)
(0, x**2 + x*y)
"""
if not u:
return dup_rr_div(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r = dmp_zero(u), f
if df < dg:
return q, r
lc_g, v = dmp_LC(g, K), u - 1
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
c, R = dmp_rr_div(lc_r, lc_g, v, K)
if not dmp_zero_p(R, v):
break
j = dr - dg
q = dmp_add_term(q, c, j, u, K)
h = dmp_mul_term(g, c, j, u, K)
r = dmp_sub(r, h, u, K)
return q, r
def dmp_prem(f, g, u, K):
"""
Polynomial pseudo-remainder in ``K[X]``.
**Examples**
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densearith import dmp_prem
>>> f = ZZ.map([[1], [1, 0], []])
>>> g = ZZ.map([[2], [2]])
>>> dmp_prem(f, g, 1, ZZ)
[[-4, 4]]
"""
if not u:
return dup_prem(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
r = f
if df < dg:
return r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
j, N = dr-dg, N-1
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
c = dmp_pow(lc_g, N, u-1, K)
return dmp_mul_term(r, c, 0, u, K)
def dmp_discriminant(f, u, K):
"""
Computes discriminant of a polynomial in `K[X]`.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y,z,t = ring("x,y,z,t", ZZ)
>>> R.dmp_discriminant(x**2*y + x*z + t)
-4*y*t + z**2
"""
if not u:
return dup_discriminant(f, K)
d, v = dmp_degree(f, u), u - 1
if d <= 0:
return dmp_zero(v)
else:
s = (-1)**((d*(d - 1)) // 2)
c = dmp_LC(f, K)
r = dmp_resultant(f, dmp_diff(f, 1, u, K), u, K)
c = dmp_mul_ground(c, K(s), v, K)
return dmp_quo(r, c, v, K)
def dmp_discriminant(f, u, K):
"""
Computes discriminant of a polynomial in ``K[X]``.
**Examples**
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.euclidtools import dmp_discriminant
>>> f = ZZ.map([[[[1]], [[]]], [[[1], []]], [[[1, 0]]]])
>>> dmp_discriminant(f, 3, ZZ)
[[[-4, 0]], [[1], [], []]]
"""
if not u:
return dup_discriminant(f, K)
d, v = dmp_degree(f, u), u-1
if d <= 0:
return dmp_zero(v)
else:
s = (-1)**((d*(d-1)) // 2)
c = dmp_LC(f, K)
r = dmp_resultant(f, dmp_diff(f, 1, u, K), u, K)
c = dmp_mul_ground(c, K(s), v, K)
return dmp_exquo(r, c, v, K)
def dmp_sqr(f, u, K):
"""Square dense polynomials in `K[X]`. """
if not u:
return dup_sqr(f, K)
df = dmp_degree(f, u)
if df < 0:
return f
h, v = [], u-1
for i in xrange(0, 2*df+1):
c = dmp_zero(v)
jmin = max(0, i-df)
jmax = min(i, df)
n = jmax - jmin + 1
jmax = jmin + n // 2 - 1
for j in xrange(jmin, jmax+1):
c = dmp_add(c, dmp_mul(f[j], f[i-j], v, K), v, K)
c = dmp_mul_ground(c, 2, v, K)
if n & 1:
elem = dmp_sqr(f[jmax+1], v, K)
c = dmp_add(c, elem, v, K)
h.append(c)
return h
def dmp_prem(f, g, u, K):
"""
Polynomial pseudo-remainder in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_prem(x**2 + x*y, 2*x + 2)
-4*y + 4
"""
if not u:
return dup_prem(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
r = f
if df < dg:
return r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
j, N = dr - dg, N - 1
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
c = dmp_pow(lc_g, N, u - 1, K)
return dmp_mul_term(r, c, 0, u, K)
def dmp_mul(f, g, u, K):
"""
Multiply dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densearith import dmp_mul
>>> f = ZZ.map([[1, 0], [1]])
>>> g = ZZ.map([[1], []])
>>> dmp_mul(f, g, 1, ZZ)
[[1, 0], [1], []]
"""
if not u:
return dup_mul(f, g, K)
if f == g:
return dmp_sqr(f, u, K)
df = dmp_degree(f, u)
if df < 0:
return f
dg = dmp_degree(g, u)
if dg < 0:
return g
h, v = [], u-1
for i in xrange(0, df+dg+1):
coeff = dmp_zero(v)
for j in xrange(max(0, i-dg), min(df, i)+1):
coeff = dmp_add(coeff, dmp_mul(f[j], g[i-j], v, K), v, K)
h.append(coeff)
return dmp_strip(h, u)
def dmp_sub(f, g, u, K):
"""
Subtract dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densearith import dmp_sub
>>> f = ZZ.map([[1], [], [1, 0]])
>>> g = ZZ.map([[1, 0], [1], []])
>>> dmp_sub(f, g, 1, ZZ)
[[-1, 1], [-1], [1, 0]]
"""
if not u:
return dup_sub(f, g, K)
df = dmp_degree(f, u)
if df < 0:
return dmp_neg(g, u, K)
dg = dmp_degree(g, u)
if dg < 0:
return f
v = u-1
if df == dg:
return dmp_strip([ dmp_sub(a, b, v, K) for a, b in zip(f, g) ], u)
else:
k = abs(df - dg)
if df > dg:
h, f = f[:k], f[k:]
else:
h, g = dmp_neg(g[:k], u, K), g[k:]
return h + [ dmp_sub(a, b, v, K) for a, b in zip(f, g) ]
def dmp_mul(f, g, u, K):
"""
Multiply dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_mul(x*y + 1, x)
x**2*y + x
"""
if not u:
return dup_mul(f, g, K)
if f == g:
return dmp_sqr(f, u, K)
df = dmp_degree(f, u)
if df < 0:
return f
dg = dmp_degree(g, u)
if dg < 0:
return g
h, v = [], u - 1
for i in xrange(0, df + dg + 1):
coeff = dmp_zero(v)
for j in xrange(max(0, i - dg), min(df, i) + 1):
coeff = dmp_add(coeff, dmp_mul(f[j], g[i - j], v, K), v, K)
h.append(coeff)
return dmp_strip(h, u)
def dmp_pdiv(f, g, u, K):
"""Polynomial pseudo-division in `K[X]`. """
if not u:
return dup_pdiv(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r = dmp_zero(u), f
if df < dg:
return q, r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
j, N = dr-dg, N-1
Q = dmp_mul_term(q, lc_g, 0, u, K)
q = dmp_add_term(Q, lc_r, j, u, K)
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
c = dmp_pow(lc_g, N, u-1, K)
q = dmp_mul_term(q, c, 0, u, K)
r = dmp_mul_term(r, c, 0, u, K)
return q, r
def dmp_sub(f, g, u, K):
"""
Subtract dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_sub(x**2 + y, x**2*y + x)
-x**2*y + x**2 - x + y
"""
if not u:
return dup_sub(f, g, K)
df = dmp_degree(f, u)
if df < 0:
return dmp_neg(g, u, K)
dg = dmp_degree(g, u)
if dg < 0:
return f
v = u - 1
if df == dg:
return dmp_strip([ dmp_sub(a, b, v, K) for a, b in zip(f, g) ], u)
else:
k = abs(df - dg)
if df > dg:
h, f = f[:k], f[k:]
else:
h, g = dmp_neg(g[:k], u, K), g[k:]
return h + [ dmp_sub(a, b, v, K) for a, b in zip(f, g) ]
def dmp_ff_div(f, g, u, K):
"""Polynomial division with remainder over a field. """
if not u:
return dup_ff_div(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r = dmp_zero(u), f
if df < dg:
return q, r
lc_g, v = dmp_LC(g, K), u-1
while True:
dr = dmp_degree(r, u)
if dr < dg:
break
lc_r = dmp_LC(r, K)
c, R = dmp_ff_div(lc_r, lc_g, v, K)
if not dmp_zero_p(R, v):
break
j = dr - dg
q = dmp_add_term(q, c, j, u, K)
h = dmp_mul_term(g, c, j, u, K)
r = dmp_sub(r, h, u, K)
return q, r
def dmp_qq_collins_resultant(f, g, u, K0):
"""
Collins's modular resultant algorithm in `Q[X]`.
Examples
========
>>> from sympy.polys import ring, QQ
>>> R, x,y = ring("x,y", QQ)
>>> f = QQ(1,2)*x + y + QQ(2,3)
>>> g = 2*x*y + x + 3
>>> R.dmp_qq_collins_resultant(f, g)
-2*y**2 - 7/3*y + 5/6
"""
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < 0 or m < 0:
return dmp_zero(u - 1)
K1 = K0.get_ring()
cf, f = dmp_clear_denoms(f, u, K0, K1)
cg, g = dmp_clear_denoms(g, u, K0, K1)
f = dmp_convert(f, u, K0, K1)
g = dmp_convert(g, u, K0, K1)
r = dmp_zz_collins_resultant(f, g, u, K1)
r = dmp_convert(r, u - 1, K1, K0)
c = K0.convert(cf**m * cg**n, K1)
return dmp_quo_ground(r, c, u - 1, K0)
def dmp_qq_collins_resultant(f, g, u, K0):
"""
Collins's modular resultant algorithm in `Q[X]`.
Examples
========
>>> from sympy.polys.domains import QQ
>>> from sympy.polys.euclidtools import dmp_qq_collins_resultant
>>> f = [[QQ(1,2)], [QQ(1), QQ(2,3)]]
>>> g = [[QQ(2), QQ(1)], [QQ(3)]]
>>> dmp_qq_collins_resultant(f, g, 1, QQ)
[-2/1, -7/3, 5/6]
"""
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < 0 or m < 0:
return dmp_zero(u-1)
K1 = K0.get_ring()
cf, f = dmp_clear_denoms(f, u, K0, K1)
cg, g = dmp_clear_denoms(g, u, K0, K1)
f = dmp_convert(f, u, K0, K1)
g = dmp_convert(g, u, K0, K1)
r = dmp_zz_collins_resultant(f, g, u, K1)
r = dmp_convert(r, u-1, K1, K0)
c = K0.convert(cf**m * cg**n, K1)
return dmp_quo_ground(r, c, u-1, K0)
def dmp_sqr(f, u, K):
"""
Square dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densearith import dmp_sqr
>>> f = ZZ.map([[1], [1, 0], [1, 0, 0]])
>>> dmp_sqr(f, 1, ZZ)
[[1], [2, 0], [3, 0, 0], [2, 0, 0, 0], [1, 0, 0, 0, 0]]
"""
if not u:
return dup_sqr(f, K)
df = dmp_degree(f, u)
if df < 0:
return f
h, v = [], u-1
for i in xrange(0, 2*df+1):
c = dmp_zero(v)
jmin = max(0, i-df)
jmax = min(i, df)
n = jmax - jmin + 1
jmax = jmin + n // 2 - 1
for j in xrange(jmin, jmax+1):
c = dmp_add(c, dmp_mul(f[j], f[i-j], v, K), v, K)
c = dmp_mul_ground(c, K(2), v, K)
if n & 1:
elem = dmp_sqr(f[jmax+1], v, K)
c = dmp_add(c, elem, v, K)
h.append(c)
return dmp_strip(h, u)
def dmp_sqr(f, u, K):
"""
Square dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_sqr(x**2 + x*y + y**2)
x**4 + 2*x**3*y + 3*x**2*y**2 + 2*x*y**3 + y**4
"""
if not u:
return dup_sqr(f, K)
df = dmp_degree(f, u)
if df < 0:
return f
h, v = [], u - 1
for i in xrange(0, 2 * df + 1):
c = dmp_zero(v)
jmin = max(0, i - df)
jmax = min(i, df)
n = jmax - jmin + 1
jmax = jmin + n // 2 - 1
for j in xrange(jmin, jmax + 1):
c = dmp_add(c, dmp_mul(f[j], f[i - j], v, K), v, K)
c = dmp_mul_ground(c, K(2), v, K)
if n & 1:
elem = dmp_sqr(f[jmax + 1], v, K)
c = dmp_add(c, elem, v, K)
h.append(c)
return dmp_strip(h, u)
def dmp_sqr(f, u, K):
"""
Square dense polynomials in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_sqr(x**2 + x*y + y**2)
x**4 + 2*x**3*y + 3*x**2*y**2 + 2*x*y**3 + y**4
"""
if not u:
return dup_sqr(f, K)
df = dmp_degree(f, u)
if df < 0:
return f
h, v = [], u - 1
for i in xrange(0, 2*df + 1):
c = dmp_zero(v)
jmin = max(0, i - df)
jmax = min(i, df)
n = jmax - jmin + 1
jmax = jmin + n // 2 - 1
for j in xrange(jmin, jmax + 1):
c = dmp_add(c, dmp_mul(f[j], f[i - j], v, K), v, K)
c = dmp_mul_ground(c, K(2), v, K)
if n & 1:
elem = dmp_sqr(f[jmax + 1], v, K)
c = dmp_add(c, elem, v, K)
h.append(c)
return dmp_strip(h, u)
def dmp_diff(f, m, u, K):
"""
``m``-th order derivative in ``x_0`` of a polynomial in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = x*y**2 + 2*x*y + 3*x + 2*y**2 + 3*y + 1
>>> R.dmp_diff(f, 1)
y**2 + 2*y + 3
>>> R.dmp_diff(f, 2)
0
"""
if not u:
return dup_diff(f, m, K)
if m <= 0:
return f
n = dmp_degree(f, u)
if n < m:
return dmp_zero(u)
deriv, v = [], u - 1
if m == 1:
for coeff in f[:-m]:
deriv.append(dmp_mul_ground(coeff, K(n), v, K))
n -= 1
else:
for coeff in f[:-m]:
k = n
for i in range(n - 1, n - m, -1):
k *= i
deriv.append(dmp_mul_ground(coeff, K(k), v, K))
n -= 1
return dmp_strip(deriv, u)
def dmp_diff(f, m, u, K):
"""
``m``-th order derivative in ``x_0`` of a polynomial in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = x*y**2 + 2*x*y + 3*x + 2*y**2 + 3*y + 1
>>> R.dmp_diff(f, 1)
y**2 + 2*y + 3
>>> R.dmp_diff(f, 2)
0
"""
if not u:
return dup_diff(f, m, K)
if m <= 0:
return f
n = dmp_degree(f, u)
if n < m:
return dmp_zero(u)
deriv, v = [], u - 1
if m == 1:
for coeff in f[:-m]:
deriv.append(dmp_mul_ground(coeff, K(n), v, K))
n -= 1
else:
for coeff in f[:-m]:
k = n
for i in range(n - 1, n - m, -1):
k *= i
deriv.append(dmp_mul_ground(coeff, K(k), v, K))
n -= 1
return dmp_strip(deriv, u)
def dmp_diff(f, m, u, K):
"""
``m``-th order derivative in ``x_0`` of a polynomial in ``K[X]``.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.densetools import dmp_diff
>>> f = ZZ.map([[1, 2, 3], [2, 3, 1]])
>>> dmp_diff(f, 1, 1, ZZ)
[[1, 2, 3]]
>>> dmp_diff(f, 2, 1, ZZ)
[[]]
"""
if not u:
return dup_diff(f, m, K)
if m <= 0:
return f
n = dmp_degree(f, u)
if n < m:
return dmp_zero(u)
deriv, v = [], u - 1
if m == 1:
for coeff in f[:-m]:
deriv.append(dmp_mul_ground(coeff, K(n), v, K))
n -= 1
else:
for coeff in f[:-m]:
k = n
for i in xrange(n - 1, n - m, -1):
k *= i
deriv.append(dmp_mul_ground(coeff, K(k), v, K))
n -= 1
return dmp_strip(deriv, u)
def dmp_sqf_p(f, u, K):
"""
Return ``True`` if ``f`` is a square-free polynomial in ``K[X]``.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_sqf_p(x**2 + 2*x*y + y**2)
False
>>> R.dmp_sqf_p(x**2 + y**2)
True
"""
if dmp_zero_p(f, u):
return True
else:
return not dmp_degree(dmp_gcd(f, dmp_diff(f, 1, u, K), u, K), u)
def dmp_sqf_p(f, u, K):
"""
Return ``True`` if ``f`` is a square-free polynomial in ``K[X]``.
**Examples**
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.sqfreetools import dmp_sqf_p
>>> f = ZZ.map([[1], [2, 0], [1, 0, 0]])
>>> dmp_sqf_p(f, 1, ZZ)
False
>>> f = ZZ.map([[1], [], [1, 0, 0]])
>>> dmp_sqf_p(f, 1, ZZ)
True
"""
if dmp_zero_p(f, u):
return True
else:
return not dmp_degree(dmp_gcd(f, dmp_diff(f, 1, u, K), u, K), u)
def dmp_prs_resultant(f, g, u, K):
"""
Resultant algorithm in `K[X]` using subresultant PRS.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = 3*x**2*y - y**3 - 4
>>> g = x**2 + x*y**3 - 9
>>> a = 3*x*y**4 + y**3 - 27*y + 4
>>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16
>>> res, prs = R.dmp_prs_resultant(f, g)
>>> res == b # resultant has n-1 variables
False
>>> res == b.drop(x)
True
>>> prs == [f, g, a, b]
True
"""
if not u:
return dup_prs_resultant(f, g, K)
if dmp_zero_p(f, u) or dmp_zero_p(g, u):
return (dmp_zero(u - 1), [])
R, S = dmp_inner_subresultants(f, g, u, K)
if dmp_degree(R[-1], u) > 0:
return (dmp_zero(u - 1), R)
return S[-1], R
def dmp_zz_modular_resultant(f, g, p, u, K):
"""
Compute resultant of `f` and `g` modulo a prime `p`.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = x + y + 2
>>> g = 2*x*y + x + 3
>>> R.dmp_zz_modular_resultant(f, g, 5)
-2*y**2 + 1
"""
if not u:
return gf_int(dup_prs_resultant(f, g, K)[0] % p, p)
v = u - 1
n = dmp_degree(f, u)
m = dmp_degree(g, u)
N = dmp_degree_in(f, 1, u)
M = dmp_degree_in(g, 1, u)
B = n*M + m*N
D, a = [K.one], -K.one
r = dmp_zero(v)
while dup_degree(D) <= B:
while True:
a += K.one
if a == p:
raise HomomorphismFailed('no luck')
F = dmp_eval_in(f, gf_int(a, p), 1, u, K)
if dmp_degree(F, v) == n:
G = dmp_eval_in(g, gf_int(a, p), 1, u, K)
if dmp_degree(G, v) == m:
break
R = dmp_zz_modular_resultant(F, G, p, v, K)
e = dmp_eval(r, a, v, K)
if not v:
R = dup_strip([R])
e = dup_strip([e])
else:
R = [R]
e = [e]
d = K.invert(dup_eval(D, a, K), p)
d = dup_mul_ground(D, d, K)
d = dmp_raise(d, v, 0, K)
c = dmp_mul(d, dmp_sub(R, e, v, K), v, K)
r = dmp_add(r, c, v, K)
r = dmp_ground_trunc(r, p, v, K)
D = dup_mul(D, [K.one, -a], K)
D = dup_trunc(D, p, K)
return r
def dmp_zz_heu_gcd(f, g, u, K):
"""
Heuristic polynomial GCD in ``Z[X]``.
Given univariate polynomials ``f`` and ``g`` in ``Z[X]``, returns
their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg``
such that::
h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h)
The algorithm is purely heuristic which means it may fail to compute
the GCD. This will be signaled by raising an exception. In this case
you will need to switch to another GCD method.
The algorithm computes the polynomial GCD by evaluating polynomials
f and g at certain points and computing (fast) integer GCD of those
evaluations. The polynomial GCD is recovered from the integer image
by interpolation. The evaluation proces reduces f and g variable by
variable into a large integer. The final step is to verify if the
interpolated polynomial is the correct GCD. This gives cofactors of
the input polynomials as a side effect.
**Examples**
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.euclidtools import dmp_zz_heu_gcd
>>> f = ZZ.map([[1], [2, 0], [1, 0, 0]])
>>> g = ZZ.map([[1], [1, 0], []])
>>> dmp_zz_heu_gcd(f, g, 1, ZZ)
([[1], [1, 0]], [[1], [1, 0]], [[1], []])
**References**
1. [Liao95]_
"""
if not u:
return dup_zz_heu_gcd(f, g, K)
result = _dmp_rr_trivial_gcd(f, g, u, K)
if result is not None:
return result
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
gcd, f, g = dmp_ground_extract(f, g, u, K)
f_norm = dmp_max_norm(f, u, K)
g_norm = dmp_max_norm(g, u, K)
B = 2 * min(f_norm, g_norm) + 29
x = max(
min(B, 99 * K.sqrt(B)),
2 * min(f_norm // abs(dmp_ground_LC(f, u, K)),
g_norm // abs(dmp_ground_LC(g, u, K))) + 2)
for i in xrange(0, HEU_GCD_MAX):
ff = dmp_eval(f, x, u, K)
gg = dmp_eval(g, x, u, K)
v = u - 1
if not (dmp_zero_p(ff, v) or dmp_zero_p(gg, v)):
h, cff, cfg = dmp_zz_heu_gcd(ff, gg, v, K)
h = _dmp_zz_gcd_interpolate(h, x, v, K)
h = dmp_ground_primitive(h, u, K)[1]
cff_, r = dmp_div(f, h, u, K)
if dmp_zero_p(r, u):
cfg_, r = dmp_div(g, h, u, K)
if dmp_zero_p(r, u):
h = dmp_mul_ground(h, gcd, u, K)
return h, cff_, cfg_
cff = _dmp_zz_gcd_interpolate(cff, x, v, K)
h, r = dmp_div(f, cff, u, K)
if dmp_zero_p(r, u):
cfg_, r = dmp_div(g, h, u, K)
if dmp_zero_p(r, u):
h = dmp_mul_ground(h, gcd, u, K)
return h, cff, cfg_
cfg = _dmp_zz_gcd_interpolate(cfg, x, v, K)
h, r = dmp_div(g, cfg, u, K)
if dmp_zero_p(r, u):
cff_, r = dmp_div(f, h, u, K)
if dmp_zero_p(r, u):
h = dmp_mul_ground(h, gcd, u, K)
return h, cff_, cfg
x = 73794 * x * K.sqrt(K.sqrt(x)) // 27011
raise HeuristicGCDFailed('no luck')
def test_dmp_degree():
assert dmp_degree([[]], 1) == -1
assert dmp_degree([[[]]], 2) == -1
assert dmp_degree([[1]], 1) == 0
assert dmp_degree([[2],[1]], 1) == 1
def dmp_inner_subresultants(f, g, u, K):
"""
Subresultant PRS algorithm in `K[X]`.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.euclidtools import dmp_inner_subresultants
>>> f = ZZ.map([[3, 0], [], [-1, 0, 0, -4]])
>>> g = ZZ.map([[1], [1, 0, 0, 0], [-9]])
>>> a = [[3, 0, 0, 0, 0], [1, 0, -27, 4]]
>>> b = [[-3, 0, 0, -12, 1, 0, -54, 8, 729, -216, 16]]
>>> R = ZZ.map([f, g, a, b])
>>> B = ZZ.map([[-1], [1], [9, 0, 0, 0, 0, 0, 0, 0, 0]])
>>> D = ZZ.map([0, 1, 1])
>>> dmp_inner_subresultants(f, g, 1, ZZ) == (R, B, D)
True
"""
if not u:
return dup_inner_subresultants(f, g, K)
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < m:
f, g = g, f
n, m = m, n
R = [f, g]
d = n - m
v = u - 1
b = dmp_pow(dmp_ground(-K.one, v), d + 1, v, K)
c = dmp_ground(-K.one, v)
B, D = [b], [d]
if dmp_zero_p(f, u) or dmp_zero_p(g, u):
return R, B, D
h = dmp_prem(f, g, u, K)
h = dmp_mul_term(h, b, 0, u, K)
while not dmp_zero_p(h, u):
k = dmp_degree(h, u)
R.append(h)
lc = dmp_LC(g, K)
p = dmp_pow(dmp_neg(lc, v, K), d, v, K)
if not d:
q = c
else:
q = dmp_pow(c, d - 1, v, K)
c = dmp_quo(p, q, v, K)
b = dmp_mul(dmp_neg(lc, v, K), dmp_pow(c, m - k, v, K), v, K)
f, g, m, d = g, h, k, m - k
B.append(b)
D.append(d)
h = dmp_prem(f, g, u, K)
h = [dmp_quo(ch, b, v, K) for ch in h]
return R, B, D
def dmp_prs_resultant(f, g, u, K):
"""
Resultant algorithm in `K[X]` using subresultant PRS.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.euclidtools import dmp_prs_resultant
>>> f = ZZ.map([[3, 0], [], [-1, 0, 0, -4]])
>>> g = ZZ.map([[1], [1, 0, 0, 0], [-9]])
>>> a = ZZ.map([[3, 0, 0, 0, 0], [1, 0, -27, 4]])
>>> b = ZZ.map([[-3, 0, 0, -12, 1, 0, -54, 8, 729, -216, 16]])
>>> dmp_prs_resultant(f, g, 1, ZZ) == (b[0], [f, g, a, b])
True
"""
if not u:
return dup_prs_resultant(f, g, K)
if dmp_zero_p(f, u) or dmp_zero_p(g, u):
return (dmp_zero(u - 1), [])
R, B, D = dmp_inner_subresultants(f, g, u, K)
if dmp_degree(R[-1], u) > 0:
return (dmp_zero(u - 1), R)
if dmp_one_p(R[-2], u, K):
return (dmp_LC(R[-1], K), R)
s, i, v = 1, 1, u - 1
p = dmp_one(v, K)
q = dmp_one(v, K)
for b, d in list(zip(B, D))[:-1]:
du = dmp_degree(R[i - 1], u)
dv = dmp_degree(R[i], u)
dw = dmp_degree(R[i + 1], u)
if du % 2 and dv % 2:
s = -s
lc, i = dmp_LC(R[i], K), i + 1
p = dmp_mul(dmp_mul(p, dmp_pow(b, dv, v, K), v, K),
dmp_pow(lc, du - dw, v, K), v, K)
q = dmp_mul(q, dmp_pow(lc, dv * (1 + d), v, K), v, K)
_, p, q = dmp_inner_gcd(p, q, v, K)
if s < 0:
p = dmp_neg(p, v, K)
i = dmp_degree(R[-2], u)
res = dmp_pow(dmp_LC(R[-1], K), i, v, K)
res = dmp_quo(dmp_mul(res, p, v, K), q, v, K)
return res, R
def dmp_zz_factor(f, u, K):
"""
Factor (non square-free) polynomials in `Z[X]`.
Given a multivariate polynomial `f` in `Z[x]` computes its complete
factorization `f_1, ..., f_n` into irreducibles over integers::
f = content(f) f_1**k_1 ... f_n**k_n
The factorization is computed by reducing the input polynomial
into a primitive square-free polynomial and factoring it using
Enhanced Extended Zassenhaus (EEZ) algorithm. Trial division
is used to recover the multiplicities of factors.
The result is returned as a tuple consisting of::
(content(f), [(f_1, k_1), ..., (f_n, k_n))
Consider polynomial `f = 2*(x**2 - y**2)`::
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_zz_factor(2*x**2 - 2*y**2)
(2, [(x - y, 1), (x + y, 1)])
In result we got the following factorization::
f = 2 (x - y) (x + y)
References
==========
.. [1] [Gathen99]_
"""
if not u:
return dup_zz_factor(f, K)
if dmp_zero_p(f, u):
return K.zero, []
cont, g = dmp_ground_primitive(f, u, K)
if dmp_ground_LC(g, u, K) < 0:
cont, g = -cont, dmp_neg(g, u, K)
if all(d <= 0 for d in dmp_degree_list(g, u)):
return cont, []
G, g = dmp_primitive(g, u, K)
factors = []
if dmp_degree(g, u) > 0:
g = dmp_sqf_part(g, u, K)
H = dmp_zz_wang(g, u, K)
factors = dmp_trial_division(f, H, u, K)
for g, k in dmp_zz_factor(G, u - 1, K)[1]:
factors.insert(0, ([g], k))
return cont, _sort_factors(factors)
def dmp_inner_subresultants(f, g, u, K):
"""
Subresultant PRS algorithm in `K[X]`.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = 3*x**2*y - y**3 - 4
>>> g = x**2 + x*y**3 - 9
>>> a = 3*x*y**4 + y**3 - 27*y + 4
>>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16
>>> prs = [f, g, a, b]
>>> sres = [[1], [1], [3, 0, 0, 0, 0], [-3, 0, 0, -12, 1, 0, -54, 8, 729, -216, 16]]
>>> R.dmp_inner_subresultants(f, g) == (prs, sres)
True
"""
if not u:
return dup_inner_subresultants(f, g, K)
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < m:
f, g = g, f
n, m = m, n
if dmp_zero_p(f, u):
return [], []
v = u - 1
if dmp_zero_p(g, u):
return [f], [dmp_ground(K.one, v)]
R = [f, g]
d = n - m
b = dmp_pow(dmp_ground(-K.one, v), d + 1, v, K)
h = dmp_prem(f, g, u, K)
h = dmp_mul_term(h, b, 0, u, K)
lc = dmp_LC(g, K)
c = dmp_pow(lc, d, v, K)
S = [dmp_ground(K.one, v), c]
c = dmp_neg(c, v, K)
while not dmp_zero_p(h, u):
k = dmp_degree(h, u)
R.append(h)
f, g, m, d = g, h, k, m - k
b = dmp_mul(dmp_neg(lc, v, K),
dmp_pow(c, d, v, K), v, K)
h = dmp_prem(f, g, u, K)
h = [ dmp_quo(ch, b, v, K) for ch in h ]
lc = dmp_LC(g, K)
if d > 1:
p = dmp_pow(dmp_neg(lc, v, K), d, v, K)
q = dmp_pow(c, d - 1, v, K)
c = dmp_quo(p, q, v, K)
else:
c = dmp_neg(lc, v, K)
S.append(dmp_neg(c, v, K))
return R, S
def dmp_zz_modular_resultant(f, g, p, u, K):
"""
Compute resultant of `f` and `g` modulo a prime `p`.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.euclidtools import dmp_zz_modular_resultant
>>> f = ZZ.map([[1], [1, 2]])
>>> g = ZZ.map([[2, 1], [3]])
>>> dmp_zz_modular_resultant(f, g, ZZ(5), 1, ZZ)
[-2, 0, 1]
"""
if not u:
return gf_int(dup_prs_resultant(f, g, K)[0] % p, p)
v = u - 1
n = dmp_degree(f, u)
m = dmp_degree(g, u)
N = dmp_degree_in(f, 1, u)
M = dmp_degree_in(g, 1, u)
B = n * M + m * N
D, a = [K.one], -K.one
r = dmp_zero(v)
while dup_degree(D) <= B:
while True:
a += K.one
if a == p:
raise HomomorphismFailed('no luck')
F = dmp_eval_in(f, gf_int(a, p), 1, u, K)
if dmp_degree(F, v) == n:
G = dmp_eval_in(g, gf_int(a, p), 1, u, K)
if dmp_degree(G, v) == m:
break
R = dmp_zz_modular_resultant(F, G, p, v, K)
e = dmp_eval(r, a, v, K)
if not v:
R = dup_strip([R])
e = dup_strip([e])
else:
R = [R]
e = [e]
d = K.invert(dup_eval(D, a, K), p)
d = dup_mul_ground(D, d, K)
d = dmp_raise(d, v, 0, K)
c = dmp_mul(d, dmp_sub(R, e, v, K), v, K)
r = dmp_add(r, c, v, K)
r = dmp_ground_trunc(r, p, v, K)
D = dup_mul(D, [K.one, -a], K)
D = dup_trunc(D, p, K)
return r
def dmp_inner_subresultants(f, g, u, K):
"""
Subresultant PRS algorithm in `K[X]`.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = 3*x**2*y - y**3 - 4
>>> g = x**2 + x*y**3 - 9
>>> a = 3*x*y**4 + y**3 - 27*y + 4
>>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16
>>> prs = [f, g, a, b]
>>> beta = [[-1], [1], [9, 0, 0, 0, 0, 0, 0, 0, 0]]
>>> delta = [0, 1, 1]
>>> R.dmp_inner_subresultants(f, g) == (prs, beta, delta)
True
"""
if not u:
return dup_inner_subresultants(f, g, K)
n = dmp_degree(f, u)
m = dmp_degree(g, u)
if n < m:
f, g = g, f
n, m = m, n
R = [f, g]
d = n - m
v = u - 1
b = dmp_pow(dmp_ground(-K.one, v), d + 1, v, K)
c = dmp_ground(-K.one, v)
B, D = [b], [d]
if dmp_zero_p(f, u) or dmp_zero_p(g, u):
return R, B, D
h = dmp_prem(f, g, u, K)
h = dmp_mul_term(h, b, 0, u, K)
while not dmp_zero_p(h, u):
k = dmp_degree(h, u)
R.append(h)
lc = dmp_LC(g, K)
p = dmp_pow(dmp_neg(lc, v, K), d, v, K)
if not d:
q = c
else:
q = dmp_pow(c, d - 1, v, K)
c = dmp_quo(p, q, v, K)
b = dmp_mul(dmp_neg(lc, v, K),
dmp_pow(c, m - k, v, K), v, K)
f, g, m, d = g, h, k, m - k
B.append(b)
D.append(d)
h = dmp_prem(f, g, u, K)
h = [ dmp_quo(ch, b, v, K) for ch in h ]
return R, B, D
def test_dmp_zz_wang():
p = ZZ(nextprime(dmp_zz_mignotte_bound(w_1, 2, ZZ)))
assert p == ZZ(6291469)
t_1, k_1, e_1 = dmp_normal([[1], []], 1, ZZ), 1, ZZ(-14)
t_2, k_2, e_2 = dmp_normal([[1, 0]], 1, ZZ), 2, ZZ(3)
t_3, k_3, e_3 = dmp_normal([[1], [1, 0]], 1, ZZ), 2, ZZ(-11)
t_4, k_4, e_4 = dmp_normal([[1], [-1, 0]], 1, ZZ), 1, ZZ(-17)
T = [t_1, t_2, t_3, t_4]
K = [k_1, k_2, k_3, k_4]
E = [e_1, e_2, e_3, e_4]
T = zip(T, K)
A = [ZZ(-14), ZZ(3)]
S = dmp_eval_tail(w_1, A, 2, ZZ)
cs, s = dup_primitive(S, ZZ)
assert cs == 1 and s == S == \
dup_normal([1036728, 915552, 55748, 105621, -17304, -26841, -644], ZZ)
assert dmp_zz_wang_non_divisors(E, cs, 4, ZZ) == [7, 3, 11, 17]
assert dup_sqf_p(s, ZZ) and dup_degree(s) == dmp_degree(w_1, 2)
_, H = dup_zz_factor_sqf(s, ZZ)
h_1 = dup_normal([44, 42, 1], ZZ)
h_2 = dup_normal([126, -9, 28], ZZ)
h_3 = dup_normal([187, 0, -23], ZZ)
assert H == [h_1, h_2, h_3]
lc_1 = dmp_normal([[-4], [-4, 0]], 1, ZZ)
lc_2 = dmp_normal([[-1, 0, 0], []], 1, ZZ)
lc_3 = dmp_normal([[1], [], [-1, 0, 0]], 1, ZZ)
LC = [lc_1, lc_2, lc_3]
assert dmp_zz_wang_lead_coeffs(w_1, T, cs, E, H, A, 2, ZZ) == (w_1, H, LC)
H_1 = [
dmp_normal(t, 0, ZZ)
for t in [[44L, 42L, 1L], [126L, -9L, 28L], [187L, 0L, -23L]]
]
H_2 = [
dmp_normal(t, 1, ZZ)
for t in [[[-4, -12], [-3, 0], [1]], [[-9, 0], [-9], [-2, 0]],
[[1, 0, -9], [], [1, -9]]]
]
H_3 = [
dmp_normal(t, 1, ZZ)
for t in [[[-4, -12], [-3, 0], [1]], [[-9, 0], [-9], [-2, 0]],
[[1, 0, -9], [], [1, -9]]]
]
c_1 = dmp_normal([-70686, -5863, -17826, 2009, 5031, 74], 0, ZZ)
c_2 = dmp_normal(
[[9, 12, -45, -108, -324], [18, -216, -810, 0],
[2, 9, -252, -288, -945], [-30, -414, 0], [2, -54, -3, 81], [12, 0]],
1, ZZ)
c_3 = dmp_normal(
[[-36, -108, 0], [-27, -36, -108], [-8, -42, 0], [-6, 0, 9], [2, 0]],
1, ZZ)
T_1 = [dmp_normal(t, 0, ZZ) for t in [[-3, 0], [-2], [1]]]
T_2 = [dmp_normal(t, 1, ZZ) for t in [[[-1, 0], []], [[-3], []], [[-6]]]]
T_3 = [dmp_normal(t, 1, ZZ) for t in [[[]], [[]], [[-1]]]]
assert dmp_zz_diophantine(H_1, c_1, [], 5, p, 0, ZZ) == T_1
assert dmp_zz_diophantine(H_2, c_2, [ZZ(-14)], 5, p, 1, ZZ) == T_2
assert dmp_zz_diophantine(H_3, c_3, [ZZ(-14)], 5, p, 1, ZZ) == T_3
factors = dmp_zz_wang_hensel_lifting(w_1, H, LC, A, p, 2, ZZ)
assert dmp_expand(factors, 2, ZZ) == w_1
def dmp_zz_factor(f, u, K):
"""
Factor (non square-free) polynomials in `Z[X]`.
Given a multivariate polynomial `f` in `Z[x]` computes its complete
factorization `f_1, ..., f_n` into irreducibles over integers::
f = content(f) f_1**k_1 ... f_n**k_n
The factorization is computed by reducing the input polynomial
into a primitive square-free polynomial and factoring it using
Enhanced Extended Zassenhaus (EEZ) algorithm. Trial division
is used to recover the multiplicities of factors.
The result is returned as a tuple consisting of::
(content(f), [(f_1, k_1), ..., (f_n, k_n))
Consider polynomial `f = 2*(x**2 - y**2)`::
>>> from sympy.polys.factortools import dmp_zz_factor
>>> from sympy.polys.domains import ZZ
>>> dmp_zz_factor([[2], [], [-2, 0, 0]], 1, ZZ)
(2, [([[1], [-1, 0]], 1), ([[1], [1, 0]], 1)])
In result we got the following factorization::
f = 2 (x - y) (x + y)
References
==========
1. [Gathen99]_
"""
if not u:
return dup_zz_factor(f, K)
if dmp_zero_p(f, u):
return K.zero, []
cont, g = dmp_ground_primitive(f, u, K)
if dmp_ground_LC(g, u, K) < 0:
cont, g = -cont, dmp_neg(g, u, K)
if all(d <= 0 for d in dmp_degree_list(g, u)):
return cont, []
G, g = dmp_primitive(g, u, K)
factors = []
if dmp_degree(g, u) > 0:
g = dmp_sqf_part(g, u, K)
H = dmp_zz_wang(g, u, K)
for h in H:
k = 0
while True:
q, r = dmp_div(f, h, u, K)
if dmp_zero_p(r, u):
f, k = q, k + 1
else:
break
factors.append((h, k))
for g, k in dmp_zz_factor(G, u - 1, K)[1]:
factors.insert(0, ([g], k))
return cont, _sort_factors(factors)
def dmp_prs_resultant(f, g, u, K):
"""
Resultant algorithm in `K[X]` using subresultant PRS.
Examples
========
>>> from sympy.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> f = 3*x**2*y - y**3 - 4
>>> g = x**2 + x*y**3 - 9
>>> a = 3*x*y**4 + y**3 - 27*y + 4
>>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16
>>> res, prs = R.dmp_prs_resultant(f, g)
>>> res == b # resultant has n-1 variables
False
>>> res == b.drop(x)
True
>>> prs == [f, g, a, b]
True
"""
if not u:
return dup_prs_resultant(f, g, K)
if dmp_zero_p(f, u) or dmp_zero_p(g, u):
return (dmp_zero(u - 1), [])
R, B, D = dmp_inner_subresultants(f, g, u, K)
if dmp_degree(R[-1], u) > 0:
return (dmp_zero(u - 1), R)
if dmp_one_p(R[-2], u, K):
return (dmp_LC(R[-1], K), R)
s, i, v = 1, 1, u - 1
p = dmp_one(v, K)
q = dmp_one(v, K)
for b, d in list(zip(B, D))[:-1]:
du = dmp_degree(R[i - 1], u)
dv = dmp_degree(R[i ], u)
dw = dmp_degree(R[i + 1], u)
if du % 2 and dv % 2:
s = -s
lc, i = dmp_LC(R[i], K), i + 1
p = dmp_mul(dmp_mul(p, dmp_pow(b, dv, v, K), v, K),
dmp_pow(lc, du - dw, v, K), v, K)
q = dmp_mul(q, dmp_pow(lc, dv*(1 + d), v, K), v, K)
_, p, q = dmp_inner_gcd(p, q, v, K)
if s < 0:
p = dmp_neg(p, v, K)
i = dmp_degree(R[-2], u)
res = dmp_pow(dmp_LC(R[-1], K), i, v, K)
res = dmp_quo(dmp_mul(res, p, v, K), q, v, K)
return res, R
