def test_PolyRing___getitem__():
R, x, y, z = ring("x,y,z", ZZ)
assert R[0:] == PolyRing("x,y,z", ZZ, lex)
assert R[1:] == PolyRing("y,z", ZZ, lex)
assert R[2:] == PolyRing("z", ZZ, lex)
assert R[3:] == ZZ
def test_PolyElement_drop():
R, x, y, z = ring("x,y,z", ZZ)
assert R(1).drop(0).ring == PolyRing("y,z", ZZ, lex)
assert R(1).drop(0).drop(0).ring == PolyRing("z", ZZ, lex)
assert isinstance(R(1).drop(0).drop(0).drop(0), R.dtype) is False
pytest.raises(ValueError, lambda: z.drop(0).drop(0).drop(0))
pytest.raises(ValueError, lambda: x.drop(0))
def test_PolyRing_is_():
R = PolyRing("x", QQ, lex)
assert R.is_univariate is True
assert R.is_multivariate is False
R = PolyRing("x,y,z", QQ, lex)
assert R.is_univariate is False
assert R.is_multivariate is True
def test_pickling_polys_rings():
# NOTE: can't use protocols < 2 because we have to execute __new__ to
# make sure caching of rings works properly.
ring = PolyRing("x,y,z", ZZ, lex)
for c in (PolyRing, ring):
check(c, exclude=[0, 1])
for c in (ring.dtype, ring.one):
check(c, exclude=[0, 1], check_attr=False) # TODO: Py3k
def __init__(self, domain_or_ring, symbols=None, order=None):
from diofant.polys.rings import PolyRing
if isinstance(domain_or_ring,
PolyRing) and symbols is None and order is None:
ring = domain_or_ring
else:
ring = PolyRing(symbols, domain_or_ring, order)
self.ring = ring
self.dtype = ring.dtype
self.gens = ring.gens
self.ngens = ring.ngens
self.symbols = ring.symbols
self.domain = ring.domain
def test_PolyRing_drop():
R, x, y, z = ring("x,y,z", ZZ)
assert R.drop(x) == PolyRing("y,z", ZZ, lex)
assert R.drop(y) == PolyRing("x,z", ZZ, lex)
assert R.drop(z) == PolyRing("x,y", ZZ, lex)
assert R.drop(0) == PolyRing("y,z", ZZ, lex)
assert R.drop(0).drop(0) == PolyRing("z", ZZ, lex)
assert R.drop(0).drop(0).drop(0) == ZZ
assert R.drop(1) == PolyRing("x,z", ZZ, lex)
assert R.drop(2) == PolyRing("x,y", ZZ, lex)
assert R.drop(2).drop(1) == PolyRing("x", ZZ, lex)
assert R.drop(2).drop(1).drop(0) == ZZ
pytest.raises(ValueError, lambda: R.drop(3))
pytest.raises(ValueError, lambda: R.drop(x).drop(y))
def test_sring():
x, y, z, t = symbols("x,y,z,t")
R = PolyRing("x,y,z", ZZ, lex)
assert sring(x + 2*y + 3*z) == (R, R.x + 2*R.y + 3*R.z)
R = PolyRing("x,y,z", QQ, lex)
assert sring(x + 2*y + z/3) == (R, R.x + 2*R.y + R.z/3)
assert sring([x, 2*y, z/3]) == (R, [R.x, 2*R.y, R.z/3])
Rt = PolyRing("t", ZZ, lex)
R = PolyRing("x,y,z", Rt, lex)
assert sring(x + 2*t*y + 3*t**2*z, x, y, z) == (R, R.x + 2*Rt.t*R.y + 3*Rt.t**2*R.z)
Rt = PolyRing("t", QQ, lex)
R = PolyRing("x,y,z", Rt, lex)
assert sring(x + t*y/2 + t**2*z/3, x, y, z) == (R, R.x + Rt.t*R.y/2 + Rt.t**2*R.z/3)
Rt = FracField("t", ZZ, lex)
R = PolyRing("x,y,z", Rt, lex)
assert sring(x + 2*y/t + t**2*z/3, x, y, z) == (R, R.x + 2*R.y/Rt.t + Rt.t**2*R.z/3)
def __new__(cls, symbols, domain, order=lex):
from diofant.polys.rings import PolyRing
ring = PolyRing(symbols, domain, order)
symbols = ring.symbols
ngens = ring.ngens
domain = ring.domain
order = ring.order
_hash = hash((cls.__name__, symbols, ngens, domain, order))
obj = _field_cache.get(_hash)
if obj is None:
obj = object.__new__(cls)
obj._hash = _hash
obj.ring = ring
obj.dtype = type("FracElement", (FracElement,), {"field": obj})
obj.symbols = symbols
obj.ngens = ngens
obj.domain = domain
obj.order = order
obj.zero = obj.dtype(ring.zero)
obj.one = obj.dtype(ring.one)
obj.gens = obj._gens()
for symbol, generator in zip(obj.symbols, obj.gens):
if isinstance(symbol, Symbol):
name = symbol.name
if not hasattr(obj, name):
setattr(obj, name, generator)
_field_cache[_hash] = obj
return obj
def test_PolyRing___init__():
x, y, z, t = map(Symbol, "xyzt")
assert len(PolyRing("x,y,z", ZZ, lex).gens) == 3
assert len(PolyRing(x, ZZ, lex).gens) == 1
assert len(PolyRing(("x", "y", "z"), ZZ, lex).gens) == 3
assert len(PolyRing((x, y, z), ZZ, lex).gens) == 3
pytest.raises(GeneratorsNeeded, lambda: PolyRing([], ZZ, lex))
pytest.raises(GeneratorsError, lambda: PolyRing(0, ZZ, lex))
assert PolyRing("x", ZZ[t], lex).domain == ZZ[t]
assert PolyRing("x", 'ZZ[t]', lex).domain == ZZ[t]
assert PolyRing("x", PolyRing("t", ZZ, lex), lex).domain == ZZ[t]
pytest.raises(GeneratorsError,
lambda: PolyRing("x", PolyRing("x", ZZ, lex), lex))
_lex = Symbol("lex")
assert PolyRing("x", ZZ, lex).order == lex
assert PolyRing("x", ZZ, _lex).order == lex
assert PolyRing("x", ZZ, 'lex').order == lex
R1 = PolyRing("x,y", ZZ, lex)
R2 = PolyRing("x,y", ZZ, lex)
R3 = PolyRing("x,y,z", ZZ, lex)
assert R1.x == R1.gens[0]
assert R1.y == R1.gens[1]
assert R1.x == R2.x
assert R1.y == R2.y
assert R1.x != R3.x
assert R1.y != R3.y
def _integrate(field=None):
irreducibles = set()
for poly in reducibles:
for z in poly.free_symbols:
if z in V:
break # should this be: `irreducibles |= \
else: # set(root_factors(poly, z, filter=field))`
continue # and the line below deleted?
# |
# V
irreducibles |= set(root_factors(poly, z, filter=field))
log_coeffs, log_part = [], []
B = _symbols('B', len(irreducibles))
# Note: the ordering matters here
for poly, b in reversed(list(ordered(zip(irreducibles, B)))):
if poly.has(*V):
poly_coeffs.append(b)
log_part.append(b * log(poly))
# TODO: Currently it's better to use symbolic expressions here instead
# of rational functions, because it's simpler and FracElement doesn't
# give big speed improvement yet. This is because cancelation is slow
# due to slow polynomial GCD algorithms. If this gets improved then
# revise this code.
candidate = poly_part / poly_denom + Add(*log_part)
h = F - _derivation(candidate) / denom
raw_numer = h.as_numer_denom()[0]
# Rewrite raw_numer as a polynomial in K[coeffs][V] where K is a field
# that we have to determine. We can't use simply atoms() because log(3),
# sqrt(y) and similar expressions can appear, leading to non-trivial
# domains.
syms = set(poly_coeffs) | set(V)
non_syms = set()
def find_non_syms(expr):
if expr.is_Integer or expr.is_Rational:
pass # ignore trivial numbers
elif expr in syms:
pass # ignore variables
elif not expr.has(*syms):
non_syms.add(expr)
elif expr.is_Add or expr.is_Mul or expr.is_Pow:
list(map(find_non_syms, expr.args))
else:
# TODO: Non-polynomial expression. This should have been
# filtered out at an earlier stage.
raise PolynomialError
try:
find_non_syms(raw_numer)
except PolynomialError:
return
else:
ground, _ = construct_domain(non_syms, field=True)
coeff_ring = PolyRing(poly_coeffs, ground)
ring = PolyRing(V, coeff_ring)
numer = ring.from_expr(raw_numer)
solution = solve_lin_sys(numer.coeffs(), coeff_ring)
if solution is None:
return
else:
solution = [(coeff_ring.symbols[coeff_ring.index(k)], v.as_expr())
for k, v in solution.items()]
return candidate.subs(solution).subs(
list(zip(poly_coeffs, [S.Zero] * len(poly_coeffs))))
def to_ring(self):
from diofant.polys.rings import PolyRing
return PolyRing(self.symbols, self.domain, self.order)