def roots_rational(f):
"""Returns a list of rational roots of a polynomial."""
try:
g = f.as_integer()[1]
except CoefficientError:
return []
LC_divs = divisors(int(g.LC))
TC_divs = divisors(int(g.TC))
if not g(S.Zero):
zeros = [S.Zero]
else:
zeros = []
for p in LC_divs:
for q in TC_divs:
zero = Rational(p, q)
if not g(zero):
zeros.append(zero)
if not g(-zero):
zeros.append(-zero)
return zeros
def roots_rational(f):
"""Returns a list of rational roots of a polynomial."""
domain = f.get_domain()
if domain.is_QQ:
_, f = f.clear_denoms()
elif domain.is_ZZ:
f = f.set_domain('QQ')
else:
return []
LC_divs = divisors(int(f.LC()))
EC_divs = divisors(int(f.EC()))
if not f.eval(S.Zero):
zeros = [S.Zero]
else:
zeros = []
for p in LC_divs:
for q in EC_divs:
zero = Rational(p, q)
if not f.eval(zero):
zeros.append(zero)
if not f.eval(-zero):
zeros.append(-zero)
return sorted(zeros, key=default_sort_key)
def _integer_basis(poly):
"""Compute coefficient basis for a polynomial over integers. """
monoms, coeffs = zip(*poly.terms())
monoms, = zip(*monoms)
coeffs = map(abs, coeffs)
if coeffs[0] < coeffs[-1]:
coeffs = list(reversed(coeffs))
else:
return None
monoms = monoms[:-1]
coeffs = coeffs[:-1]
divs = reversed(divisors(gcd_list(coeffs))[1:])
try:
div = divs.next()
except StopIteration:
return None
while True:
for monom, coeff in zip(monoms, coeffs):
if coeff % div**monom != 0:
try:
div = divs.next()
except StopIteration:
return None
else:
break
else:
return div
def calc_recurrence_seq(p):
decimal.getcontext().prec = p - 1
r = reciprocal(p)
for d in ntheory.divisors(p - 1):
if d == 1 or d == p - 1:
continue
if r[:d] == r[d:2 * d]:
return r[:d]
return r[:p - 1]
def MultiOrder(n):
div = divisors(n)
if list(set(div).intersection((2,5,10))) != []:
return None
order=1
product = 10
while product != 1:
order+=1
product = (product*10)%n
return order
def _integer_basis(poly):
"""Compute coefficient basis for a polynomial over integers.
Returns the integer ``div`` such that substituting ``x = div*y``
``p(x) = m*q(y)`` where the coefficients of ``q`` are smaller
than those of ``p``.
For example ``x**5 + 512*x + 1024 = 0``
with ``div = 4`` becomes ``y**5 + 2*y + 1 = 0``
Returns the integer ``div`` or ``None`` if there is no possible scaling.
Examples
========
>>> from sympy.polys import Poly
>>> from sympy.abc import x
>>> from sympy.polys.polyroots import _integer_basis
>>> p = Poly(x**5 + 512*x + 1024, x, domain='ZZ')
>>> _integer_basis(p)
4
"""
monoms, coeffs = list(zip(*poly.terms()))
monoms, = list(zip(*monoms))
coeffs = list(map(abs, coeffs))
if coeffs[0] < coeffs[-1]:
coeffs = list(reversed(coeffs))
n = monoms[0]
monoms = [n - i for i in reversed(monoms)]
else:
return None
monoms = monoms[:-1]
coeffs = coeffs[:-1]
divs = reversed(divisors(gcd_list(coeffs))[1:])
try:
div = next(divs)
except StopIteration:
return None
while True:
for monom, coeff in zip(monoms, coeffs):
if coeff % div**monom != 0:
try:
div = next(divs)
except StopIteration:
return None
else:
break
else:
return div
def divisors_and_divisor_count():
assert divisors(-1) == [1]
assert divisors(0) == []
assert divisors(1) == [1]
assert divisors(2) == [1, 2]
assert divisors(3) == [1, 3]
assert divisors(17) == [1, 17]
assert divisors(10) == [1, 2, 5, 10]
assert divisors(100) == [1, 2, 4, 5, 10, 20, 25, 50, 100]
assert divisors(101) == [1, 101]
assert divisor_count(0) == 0
assert divisor_count(-1) == 1
assert divisor_count(1) == 1
assert divisor_count(6) == 4
assert divisor_count(12) == 6
def find_rational_roots(f):
if not all(x.is_rational for x in f.all_coeffs()):
return []
a = f.nth(0)
b = f.nth(f.degree())
result = []
for p in divisors(a):
for q in divisors(b):
if igcd(p, q) == 1:
if f(Rational(p, q)) == 0:
result += [Rational(p, q)]
if f(Rational(-p, q)) == 0:
result += [Rational(-p, q)]
if len(result) > 0:
add_comment("Use the rational root test")
add_comment("Test all rational numbers in the form p/q")
add_comment("where p is a divisor of {} and q is a divisor of {}", str(a), str(b))
add_comment("We have the following roots")
for r in result:
add_eq(f.gen, r)
return result
def test_divisors_and_divisor_count():
assert divisors(-1) == [1]
assert divisors(0) == []
assert divisors(1) == [1]
assert divisors(2) == [1, 2]
assert divisors(3) == [1, 3]
assert divisors(17) == [1, 17]
assert divisors(10) == [1, 2, 5, 10]
assert divisors(100) == [1, 2, 4, 5, 10, 20, 25, 50, 100]
assert divisors(101) == [1, 101]
assert divisor_count(0) == 0
assert divisor_count(-1) == 1
assert divisor_count(1) == 1
assert divisor_count(6) == 4
assert divisor_count(12) == 6
assert divisor_count(180, 3) == divisor_count(180//3)
assert divisor_count(2*3*5, 7) == 0
def _inv_totient_estimate(m):
"""
Find ``(L, U)`` such that ``L <= phi^-1(m) <= U``.
Examples
========
>>> from sympy.polys.polyroots import _inv_totient_estimate
>>> _inv_totient_estimate(192)
(192, 840)
>>> _inv_totient_estimate(400)
(400, 1750)
"""
primes = [ d + 1 for d in divisors(m) if isprime(d + 1) ]
a, b = 1, 1
for p in primes:
a *= p
b *= p - 1
L = m
U = int(math.ceil(m*(float(a)/b)))
P = p = 2
primes = []
while P <= U:
p = nextprime(p)
primes.append(p)
P *= p
P //= p
b = 1
for p in primes[:-1]:
b *= p - 1
U = int(math.ceil(m*(float(P)/b)))
return L, U
def test_factorint():
assert sorted(factorint(123456).items()) == [(2, 6), (3, 1), (643, 1)]
assert primefactors(123456) == [2, 3, 643]
assert factorint(-16) == {-1:1, 2:4}
assert factorint(2**(2**6) + 1) == {274177:1, 67280421310721:1}
assert factorint(5951757) == {3:1, 7:1, 29:2, 337:1}
assert factorint(64015937) == {7993:1, 8009:1}
assert divisors(1) == [1]
assert divisors(2) == [1, 2]
assert divisors(3) == [1, 3]
assert divisors(10) == [1, 2, 5, 10]
assert divisors(100) == [1, 2, 4, 5, 10, 20, 25, 50, 100]
assert divisors(101) == [1, 101]
assert factorint(0) == {0:1}
assert factorint(1) == {}
assert factorint(-1) == {-1:1}
assert factorint(-2) == {-1:1, 2:1}
assert factorint(-16) == {-1:1, 2:4}
assert factorint(2) == {2:1}
assert factorint(126) == {2:1, 3:2, 7:1}
assert factorint(123456) == {2:6, 3:1, 643:1}
assert factorint(5951757) == {3:1, 7:1, 29:2, 337:1}
assert factorint(64015937) == {7993:1, 8009:1}
assert factorint(2**(2**6) + 1) == {274177:1, 67280421310721:1}
assert multiproduct(factorint(fac(200))) == fac(200)
for b, e in factorint(fac(150)).items():
assert e == fac_multiplicity(150, b)
assert factorint(103005006059**7) == {103005006059:7}
assert factorint(31337**191) == {31337:191}
assert factorint(2**1000 * 3**500 * 257**127 * 383**60) == \
{2:1000, 3:500, 257:127, 383:60}
assert len(factorint(fac(10000))) == 1229
assert factorint(12932983746293756928584532764589230) == \
{2: 1, 5: 1, 73: 1, 727719592270351: 1, 63564265087747: 1, 383: 1}
assert factorint(727719592270351) == {727719592270351:1}
assert factorint(2**64+1, use_trial=False) == factorint(2**64+1)
for n in range(60000):
assert multiproduct(factorint(n)) == n
assert pollard_rho(2**64+1, seed=1) == 274177
assert pollard_rho(19, seed=1) is None
assert factorint(3,2) == {3: 1}
assert factorint(12345) == {3: 1, 5: 1, 823: 1}
assert factorint(12345, 3) == {12345: 1} # there are no factors less than 3
def test_factor():
assert trial(1) == []
assert trial(2) == [(2,1)]
assert trial(3) == [(3,1)]
assert trial(4) == [(2,2)]
assert trial(5) == [(5,1)]
assert trial(128) == [(2,7)]
assert trial(720) == [(2,4), (3,2), (5,1)]
assert factorint(123456) == [(2, 6), (3, 1), (643, 1)]
assert primefactors(123456) == [2, 3, 643]
assert factorint(-16) == [(-1, 1), (2, 4)]
assert factorint(2**(2**6) + 1) == [(274177, 1), (67280421310721, 1)]
assert factorint(5951757) == [(3, 1), (7, 1), (29, 2), (337, 1)]
assert factorint(64015937) == [(7993, 1), (8009, 1)]
assert divisors(1) == [1]
assert divisors(2) == [1, 2]
assert divisors(3) == [1, 3]
assert divisors(10) == [1, 2, 5, 10]
assert divisors(100) == [1, 2, 4, 5, 10, 20, 25, 50, 100]
assert divisors(101) == [1, 101]
assert pollard_rho(2**64+1, max_iters=1, seed=1) == 274177
assert pollard_rho(19) is None
def calc_some(p):
if p <= 5:
raise ValueError("p must be larger than 5")
if not sympy.isprime(p):
raise ValueError("specify prime. actual p = {}, ntheory.divisors = {}".format(p, ntheory.divisors(p)))
r = reciprocal(p)
seq = calc_recurrence_seq(p)
d = len(seq)
former = r[:d // 2]
latter = r[d // 2:d]
if d % 2 == 0:
print('length of recurrence is even')
print('1/{} = '.format(p), r)
print('former = ', former)
print('latter = ', latter)
print('former + latter =\n', Decimal(former) + Decimal(latter))
else:
print('length of recurrence is not even. In fact')
print('1/{}'.format(p), r)
print('seq = ', seq)
print('len(seq) = ', len(seq))
print('But you may find something')
if latter[0] == 9:
print("you're lucky")
print('former = ', former)
print('latter = ', latter)
print('former + latter =\n', Decimal(former) + Decimal(latter))
def test_divisors():
assert divisors(28) == [1, 2, 4, 7, 14, 28]
assert [x for x in divisors(3*5*7, 1)] == [1, 3, 5, 15, 7, 21, 35, 105]
assert divisors(0) == []
def test_issue_6981():
S = set(divisors(4)).union(set(divisors(Integer(2))))
assert S == set([1,2,4])
from sympy.ntheory import divisors
import numpy as np
sum = 0
for i in xrange(1,10000):
divSum = np.sum(divisors(i)[:-1])
if i == np.sum(divisors(divSum)[:-1]) and i !=divSum:
sum += i
print sum
def func(n):
return sum(f(d) * g(n // d) for d in nthry.divisors(n, True))
def test_issue3882():
S = set(divisors(4)).union(set(divisors(Integer(2))))
assert S == set([1, 2, 4])
def A147811(p):
return set(
[p * (p + d) * (p + (p * p + 1) / d) for d in divisors(p * p + 1)])
def test_issue_6981():
S = set(divisors(4)).union(set(divisors(Integer(2))))
assert S == {1, 2, 4}
def _integer_basis(poly):
"""Compute coefficient basis for a polynomial over integers.
Returns the integer ``div`` such that substituting ``x = div*y``
``p(x) = m*q(y)`` where the coefficients of ``q`` are smaller
than those of ``p``.
For example ``x**5 + 512*x + 1024 = 0``
with ``div = 4`` becomes ``y**5 + 2*y + 1 = 0``
Returns the integer ``div`` or ``None`` if there is no possible scaling.
Examples
========
>>> from sympy.polys import Poly
>>> from sympy.abc import x
>>> from sympy.polys.polyroots import _integer_basis
>>> p = Poly(x**5 + 512*x + 1024, x, domain='ZZ')
>>> _integer_basis(p)
4
"""
monoms, coeffs = list(zip(*poly.terms()))
monoms, = list(zip(*monoms))
coeffs = list(map(abs, coeffs))
if coeffs[0] < coeffs[-1]:
coeffs = list(reversed(coeffs))
n = monoms[0]
monoms = [n - i for i in reversed(monoms)]
else:
return None
monoms = monoms[:-1]
coeffs = coeffs[:-1]
# Special case for two-term polynominals
if len(monoms) == 1:
r = Pow(coeffs[0], S.One / monoms[0])
if r.is_Integer:
return int(r)
else:
return None
divs = reversed(divisors(gcd_list(coeffs))[1:])
try:
div = next(divs)
except StopIteration:
return None
while True:
for monom, coeff in zip(monoms, coeffs):
if coeff % div**monom != 0:
try:
div = next(divs)
except StopIteration:
return None
else:
break
else:
return div
def test_divisors():
assert divisors(28) == [1, 2, 4, 7, 14, 28]
assert [x for x in divisors(3 * 5 * 7, 1)] == [1, 3, 5, 15, 7, 21, 35, 105]
assert divisors(0) == []
sympy.ntheory.divisors is used to generate the divisors of each cube as it is much faster than a homegrown algorithm.
This program outputs the correct answer in approximately 10 minutes.
'''
from math import sqrt
from sympy.ntheory import divisors
sum_ = 0
found = 0
for d in range(1, 10**6):
cube = d**3
sqrt_cube = sqrt(cube)
for a in divisors(cube):
if a >= sqrt_cube:
break
b, remainder = divmod(cube, a)
if remainder == 0:
n = a + b
if n > 10**12:
continue
sqrt_n = sqrt(n)
if sqrt_n.is_integer(
) and a < d and n % d == a: # the last part is to make sure this is actually a solution
sum_ += n
found += 1
def g(n):
divs = nthry.divisors(n)[:-1]
x = -sum(f(n // d) * g(d) for d in divs) if divs else 1
return x / f(1)
