def Pow(expr, assumptions):
"""
Real**Integer -> Real
Positive**Real -> Real
Real**(Integer/Even) -> Real if base is nonnegative
Real**(Integer/Odd) -> Real
Real**Imaginary -> ?
Imaginary**Real -> ?
Real**Real -> ?
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if ask(Q.odd(expr.exp), assumptions):
return False
elif ask(Q.even(expr.exp), assumptions):
return True
elif ask(Q.real(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if expr.exp.is_Rational and \
ask(Q.even(expr.exp.q), assumptions):
return ask(Q.positive(expr.base), assumptions)
elif ask(Q.integer(expr.exp), assumptions):
return True
elif ask(Q.positive(expr.base), assumptions):
return True
elif ask(Q.negative(expr.base), assumptions):
return False
def test_float_1():
z = 1.0
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == True
assert ask(Q.rational(z)) == True
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == False
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == True
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == True
z = 7.2123
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == True
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == False
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
def Pow(expr, assumptions):
"""
Imaginary**integer -> Imaginary if integer % 2 == 1
Imaginary**integer -> real if integer % 2 == 0
Imaginary**Imaginary -> ?
Imaginary**Real -> ?
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if ask(Q.odd(expr.exp), assumptions):
return True
elif ask(Q.even(expr.exp), assumptions):
return False
elif ask(Q.real(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if expr.exp.is_Rational and \
ask(Q.even(expr.exp.q), assumptions):
return ask(Q.negative(expr.base),assumptions)
elif ask(Q.integer(expr.exp), assumptions):
return False
elif ask(Q.positive(expr.base), assumptions):
return False
elif ask(Q.negative(expr.base), assumptions):
return True
def test_negative():
x, y = symbols('x,y')
assert ask(Q.negative(x), Q.negative(x)) == True
assert ask(Q.negative(x), Q.positive(x)) == False
assert ask(Q.negative(x), ~Q.real(x)) == False
assert ask(Q.negative(x), Q.prime(x)) == False
assert ask(Q.negative(x), ~Q.prime(x)) == None
assert ask(Q.negative(-x), Q.positive(x)) == True
assert ask(Q.negative(-x), ~Q.positive(x)) == None
assert ask(Q.negative(-x), Q.negative(x)) == False
assert ask(Q.negative(-x), Q.positive(x)) == True
assert ask(Q.negative(x-1), Q.negative(x)) == True
assert ask(Q.negative(x+y)) == None
assert ask(Q.negative(x+y), Q.negative(x)) == None
assert ask(Q.negative(x+y), Q.negative(x) & Q.negative(y)) == True
assert ask(Q.negative(x**2)) == None
assert ask(Q.negative(x**2), Q.real(x)) == False
assert ask(Q.negative(x**1.4), Q.real(x)) == None
assert ask(Q.negative(x*y)) == None
assert ask(Q.negative(x*y), Q.positive(x) & Q.positive(y)) == False
assert ask(Q.negative(x*y), Q.positive(x) & Q.negative(y)) == True
assert ask(Q.negative(x*y), Q.complex(x) & Q.complex(y)) == None
assert ask(Q.negative(x**y)) == None
assert ask(Q.negative(x**y), Q.negative(x) & Q.even(y)) == False
assert ask(Q.negative(x**y), Q.negative(x) & Q.odd(y)) == True
assert ask(Q.negative(x**y), Q.positive(x) & Q.integer(y)) == False
assert ask(Q.negative(Abs(x))) == False
def test_functions_in_assumptions():
from sympy.logic.boolalg import Equivalent, Xor
x = symbols("x")
assert ask(x, Q.negative, Q.real(x) >> Q.positive(x)) is False
assert ask(x, Q.negative, Equivalent(Q.real(x), Q.positive(x))) is False
assert ask(x, Q.negative, Xor(Q.real(x), Q.negative(x))) is False
def test_positive():
x, y, z, w = symbols('x,y,z,w')
assert ask(Q.positive(x), Q.positive(x)) == True
assert ask(Q.positive(x), Q.negative(x)) == False
assert ask(Q.positive(x), Q.nonzero(x)) == None
assert ask(Q.positive(-x), Q.positive(x)) == False
assert ask(Q.positive(-x), Q.negative(x)) == True
assert ask(Q.positive(x+y), Q.positive(x) & Q.positive(y)) == True
assert ask(Q.positive(x+y), Q.positive(x) & Q.negative(y)) == None
assert ask(Q.positive(2*x), Q.positive(x)) == True
assumptions = Q.positive(x) & Q.negative(y) & Q.negative(z) & Q.positive(w)
assert ask(Q.positive(x*y*z)) == None
assert ask(Q.positive(x*y*z), assumptions) == True
assert ask(Q.positive(-x*y*z), assumptions) == False
assert ask(Q.positive(x**2), Q.positive(x)) == True
assert ask(Q.positive(x**2), Q.negative(x)) == True
#exponential
assert ask(Q.positive(exp(x)), Q.real(x)) == True
assert ask(Q.positive(x + exp(x)), Q.real(x)) == None
#absolute value
assert ask(Q.positive(Abs(x))) == None # Abs(0) = 0
assert ask(Q.positive(Abs(x)), Q.positive(x)) == True
def test_refine():
m0 = OperationsOnlyMatrix([[Abs(x)**2, sqrt(x**2)],
[sqrt(x**2)*Abs(y)**2, sqrt(y**2)*Abs(x)**2]])
m1 = m0.refine(Q.real(x) & Q.real(y))
assert m1 == Matrix([[x**2, Abs(x)], [y**2*Abs(x), x**2*Abs(y)]])
m1 = m0.refine(Q.positive(x) & Q.positive(y))
assert m1 == Matrix([[x**2, x], [x*y**2, x**2*y]])
m1 = m0.refine(Q.negative(x) & Q.negative(y))
assert m1 == Matrix([[x**2, -x], [-x*y**2, -x**2*y]])
def Pow(expr, assumptions):
"""
Real**Integer -> Real
Positive**Real -> Real
Real**(Integer/Even) -> Real if base is nonnegative
Real**(Integer/Odd) -> Real
Imaginary**(Integer/Even) -> Real
Imaginary**(Integer/Odd) -> not Real
Imaginary**Real -> ? since Real could be 0 (giving real) or 1 (giving imaginary)
b**Imaginary -> Real if log(b) is imaginary and b != 0 and exponent != integer multiple of I*pi/log(b)
Real**Real -> ? e.g. sqrt(-1) is imaginary and sqrt(2) is not
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
if expr.base.func == exp:
if ask(Q.imaginary(expr.base.args[0]), assumptions):
if ask(Q.imaginary(expr.exp), assumptions):
return True
# If the i = (exp's arg)/(I*pi) is an integer or half-integer
# multiple of I*pi then 2*i will be an integer. In addition,
# exp(i*I*pi) = (-1)**i so the overall realness of the expr
# can be determined by replacing exp(i*I*pi) with (-1)**i.
i = expr.base.args[0]/I/pi
if ask(Q.integer(2*i), assumptions):
return ask(Q.real(((-1)**i)**expr.exp), assumptions)
return
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
odd = ask(Q.odd(expr.exp), assumptions)
if odd is not None:
return not odd
return
if ask(Q.imaginary(expr.exp), assumptions):
imlog = ask(Q.imaginary(log(expr.base)), assumptions)
if imlog is not None:
# I**i -> real, log(I) is imag;
# (2*I)**i -> complex, log(2*I) is not imag
return imlog
if ask(Q.real(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if expr.exp.is_Rational and \
ask(Q.even(expr.exp.q), assumptions):
return ask(Q.positive(expr.base), assumptions)
elif ask(Q.integer(expr.exp), assumptions):
return True
elif ask(Q.positive(expr.base), assumptions):
return True
elif ask(Q.negative(expr.base), assumptions):
return False
def test_I():
I = S.ImaginaryUnit
z = I
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == False
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == False
assert ask(Q.imaginary(z)) == True
assert ask(Q.positive(z)) == False
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
z = 1 + I
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == False
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == False
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == False
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
z = I*(1+I)
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == False
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == False
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == False
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
def Pow(expr, assumptions):
"""
Imaginary**Odd -> Imaginary
Imaginary**Even -> Real
b**Imaginary -> !Imaginary if exponent is an integer multiple of I*pi/log(b)
Imaginary**Real -> ?
Positive**Real -> Real
Negative**Integer -> Real
Negative**(Integer/2) -> Imaginary
Negative**Real -> not Imaginary if exponent is not Rational
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
if expr.base.func == exp:
if ask(Q.imaginary(expr.base.args[0]), assumptions):
if ask(Q.imaginary(expr.exp), assumptions):
return False
i = expr.base.args[0]/I/pi
if ask(Q.integer(2*i), assumptions):
return ask(Q.imaginary(((-1)**i)**expr.exp), assumptions)
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
odd = ask(Q.odd(expr.exp), assumptions)
if odd is not None:
return odd
return
if ask(Q.imaginary(expr.exp), assumptions):
imlog = ask(Q.imaginary(log(expr.base)), assumptions)
if imlog is not None:
return False # I**i -> real; (2*I)**i -> complex ==> not imaginary
if ask(Q.real(expr.base) & Q.real(expr.exp), assumptions):
if ask(Q.positive(expr.base), assumptions):
return False
else:
rat = ask(Q.rational(expr.exp), assumptions)
if not rat:
return rat
if ask(Q.integer(expr.exp), assumptions):
return False
else:
half = ask(Q.integer(2*expr.exp), assumptions)
if half:
return ask(Q.negative(expr.base), assumptions)
return half
def test_extended_real():
x = symbols('x')
assert ask(Q.extended_real(x), Q.positive(x)) == True
assert ask(Q.extended_real(-x), Q.positive(x)) == True
assert ask(Q.extended_real(-x), Q.negative(x)) == True
assert ask(Q.extended_real(x+S.Infinity), Q.real(x)) == True
def refine_abs(expr, assumptions):
"""
Handler for the absolute value.
Examples
========
>>> from sympy import Symbol, Q, refine, Abs
>>> from sympy.assumptions.refine import refine_abs
>>> from sympy.abc import x
>>> refine_abs(Abs(x), Q.real(x))
>>> refine_abs(Abs(x), Q.positive(x))
x
>>> refine_abs(Abs(x), Q.negative(x))
-x
"""
from sympy.core.logic import fuzzy_not
arg = expr.args[0]
if ask(Q.real(arg), assumptions) and fuzzy_not(ask(Q.negative(arg), assumptions)):
# if it's nonnegative
return arg
if ask(Q.negative(arg), assumptions):
return -arg
def Basic(expr, assumptions):
_real = ask(Q.real(expr), assumptions)
if _real:
_rational = ask(Q.rational(expr), assumptions)
if _rational is None: return None
return not _rational
else: return _real
def Basic(expr, assumptions):
if expr.is_number:
notpositive = fuzzy_not(AskPositiveHandler._number(expr, assumptions))
if notpositive:
return ask(Q.real(expr), assumptions)
else:
return notpositive
def Pow(expr, assumptions):
"""
Real ** Even -> NonNegative
Real ** Odd -> same_as_base
NonNegative ** Positive -> NonNegative
"""
if expr.is_number:
return AskNegativeHandler._number(expr, assumptions)
if ask(Q.real(expr.base), assumptions):
if ask(Q.positive(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
return False
if ask(Q.even(expr.exp), assumptions):
return False
if ask(Q.odd(expr.exp), assumptions):
return ask(Q.negative(expr.base), assumptions)
def refine_atan2(expr, assumptions):
"""
Handler for the atan2 function
Examples
========
>>> from sympy import Symbol, Q, refine, atan2
>>> from sympy.assumptions.refine import refine_atan2
>>> from sympy.abc import x, y
>>> refine_atan2(atan2(y,x), Q.real(y) & Q.positive(x))
atan(y/x)
>>> refine_atan2(atan2(y,x), Q.negative(y) & Q.negative(x))
atan(y/x) - pi
>>> refine_atan2(atan2(y,x), Q.positive(y) & Q.negative(x))
atan(y/x) + pi
"""
from sympy.functions.elementary.complexes import atan
from sympy.core import S
y, x = expr.args
if ask(Q.real(y) & Q.positive(x), assumptions):
return atan(y / x)
elif ask(Q.negative(y) & Q.negative(x), assumptions):
return atan(y / x) - S.Pi
elif ask(Q.positive(y) & Q.negative(x), assumptions):
return atan(y / x) + S.Pi
else:
return expr
def reduce_abs_inequality(expr, rel, gen, assume=True):
"""Reduce an inequality with nested absolute values. """
if not ask(Q.real(gen), assumptions=assume):
raise NotImplementedError("can't solve inequalities with absolute values of a complex variable")
def bottom_up_scan(expr):
exprs = []
if expr.is_Add or expr.is_Mul:
op = expr.__class__
for arg in expr.args:
_exprs = bottom_up_scan(arg)
if not exprs:
exprs = _exprs
else:
args = []
for expr, conds in exprs:
for _expr, _conds in _exprs:
args.append((op(expr, _expr), conds + _conds))
exprs = args
elif expr.is_Pow:
n = expr.exp
if not n.is_Integer or n < 0:
raise ValueError("only non-negative integer powers are allowed")
_exprs = bottom_up_scan(expr.base)
for expr, conds in _exprs:
exprs.append((expr ** n, conds))
elif isinstance(expr, Abs):
_exprs = bottom_up_scan(expr.args[0])
for expr, conds in _exprs:
exprs.append((expr, conds + [Ge(expr, 0)]))
exprs.append((-expr, conds + [Lt(expr, 0)]))
else:
exprs = [(expr, [])]
return exprs
exprs = bottom_up_scan(expr)
mapping = {"<": ">", "<=": ">="}
inequalities = []
for expr, conds in exprs:
if rel not in mapping.keys():
expr = Relational(expr, 0, rel)
else:
expr = Relational(-expr, 0, mapping[rel])
inequalities.append([expr] + conds)
return reduce_poly_inequalities(inequalities, gen, assume)
def log(expr, assumptions):
r = ask(Q.real(expr.args[0]), assumptions)
if r is not True:
return r
if ask(Q.positive(expr.args[0] - 1), assumptions):
return True
if ask(Q.negative(expr.args[0] - 1), assumptions):
return False
def Pow(expr, assumptions):
"""
Imaginary**integer/odd -> Imaginary
Imaginary**integer/even -> Real if integer % 2 == 0
b**Imaginary -> !Imaginary if exponent is an integer multiple of I*pi/log(b)
Imaginary**Real -> ?
Negative**even root -> Imaginary
Negative**odd root -> Real
Negative**Real -> Imaginary
Real**Integer -> Real
Real**Positive -> Real
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
if expr.base.func == C.exp:
if ask(Q.imaginary(expr.base.args[0]), assumptions):
if ask(Q.imaginary(expr.exp), assumptions):
return False
i = expr.base.args[0]/I/pi
if ask(Q.integer(2*i), assumptions):
return ask(Q.imaginary(((-1)**i)**expr.exp), assumptions)
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
odd = ask(Q.odd(expr.exp), assumptions)
if odd is not None:
return odd
return
if ask(Q.imaginary(expr.exp), assumptions):
imlog = ask(Q.imaginary(C.log(expr.base)), assumptions)
if imlog is not None:
return False # I**i -> real; (2*I)**i -> complex ==> not imaginary
if ask(Q.real(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if ask(Q.rational(expr.exp) & Q.even(denom(expr.exp)), assumptions):
return ask(Q.negative(expr.base), assumptions)
elif ask(Q.integer(expr.exp), assumptions):
return False
elif ask(Q.positive(expr.base), assumptions):
return False
elif ask(Q.negative(expr.base), assumptions):
return True
def reduce_poly_inequalities(exprs, gen, assume=True, relational=True):
"""Reduce a system of polynomial inequalities with rational coefficients. """
exact = True
polys = []
for _exprs in exprs:
_polys = []
for expr in _exprs:
if isinstance(expr, tuple):
expr, rel = expr
else:
if expr.is_Relational:
expr, rel = expr.lhs - expr.rhs, expr.rel_op
else:
expr, rel = expr, '=='
poly = Poly(expr, gen)
if not poly.get_domain().is_Exact:
poly, exact = poly.to_exact(), False
domain = poly.get_domain()
if not (domain.is_ZZ or domain.is_QQ):
raise NotImplementedError("inequality solving is not supported over %s" % domain)
_polys.append((poly, rel))
polys.append(_polys)
solution = solve_poly_inequalities(polys)
if isinstance(solution, Union):
intervals = list(solution.args)
elif isinstance(solution, Interval):
intervals = [solution]
else:
intervals = []
if not exact:
intervals = map(interval_evalf, intervals)
if not relational:
return intervals
real = ask(Q.real(gen), assumptions=assume)
def relationalize(gen):
return Or(*[ i.as_relational(gen) for i in intervals ])
if not real:
result = And(relationalize(re(gen)), Eq(im(gen), 0))
else:
result = relationalize(gen)
return result
def Basic(expr, assumptions):
if ask(Q.real(expr)) is False:
return False
if expr.is_number:
# if there are no symbols just evalf
i = expr.evalf(2)
def nonz(i):
if i._prec != 1:
return i != 0
return fuzzy_or(nonz(i) for i in i.as_real_imag())
def test_integer():
x = symbols('x')
assert ask(Q.integer(x)) == None
assert ask(Q.integer(x), Q.integer(x)) == True
assert ask(Q.integer(x), ~Q.integer(x)) == False
assert ask(Q.integer(x), ~Q.real(x)) == False
assert ask(Q.integer(x), ~Q.positive(x)) == None
assert ask(Q.integer(x), Q.even(x) | Q.odd(x)) == True
assert ask(Q.integer(2*x), Q.integer(x)) == True
assert ask(Q.integer(2*x), Q.even(x)) == True
assert ask(Q.integer(2*x), Q.prime(x)) == True
assert ask(Q.integer(2*x), Q.rational(x)) == None
assert ask(Q.integer(2*x), Q.real(x)) == None
assert ask(Q.integer(sqrt(2)*x), Q.integer(x)) == False
assert ask(Q.integer(x/2), Q.odd(x)) == False
assert ask(Q.integer(x/2), Q.even(x)) == True
assert ask(Q.integer(x/3), Q.odd(x)) == None
assert ask(Q.integer(x/3), Q.even(x)) == None
def Pow(expr, assumptions):
if expr.is_number:
return expr.evalf() > 0
if ask(Q.positive(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
return True
if ask(Q.negative(expr.base), assumptions):
if ask(Q.even(expr.exp), assumptions):
return True
if ask(Q.even(expr.exp), assumptions):
return False
def Pow(expr, assumptions):
"""
Real**Integer -> Real
Positive**Real -> Real
Real**(Integer/Even) -> Real if base is nonnegative
Real**(Integer/Odd) -> Real
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
if ask(Q.real(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
return True
elif expr.exp.is_Rational:
if (expr.exp.q % 2 == 0):
return ask(Q.real(expr.base), assumptions) and \
not ask(Q.negative(expr.base), assumptions)
else: return True
elif ask(Q.real(expr.exp), assumptions):
if ask(Q.positive(expr.base), assumptions):
return True
def Pow(expr, assumptions):
if expr.is_number:
return AskPositiveHandler._number(expr, assumptions)
if ask(Q.positive(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
return True
if ask(Q.negative(expr.base), assumptions):
if ask(Q.even(expr.exp), assumptions):
return True
if ask(Q.odd(expr.exp), assumptions):
return False
def log(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
if ask(Q.positive(expr.args[0]), assumptions):
return False
return
# XXX it should be enough to do
# return ask(Q.nonpositive(expr.args[0]), assumptions)
# but ask(Q.nonpositive(exp(x)), Q.imaginary(x)) -> None;
# it should return True since exp(x) will be either 0 or complex
if expr.args[0].func == exp:
if expr.args[0].args[0] in [I, -I]:
return True
im = ask(Q.imaginary(expr.args[0]), assumptions)
if im is False:
return False
def reduce_poly_inequalities(exprs, gen, assume=True, relational=True):
"""Reduce a system of polynomial inequalities with rational coefficients. """
exact = True
polys = []
for _exprs in exprs:
_polys = []
for expr in _exprs:
if isinstance(expr, tuple):
expr, rel = expr
else:
if expr.is_Relational:
expr, rel = expr.lhs - expr.rhs, expr.rel_op
else:
expr, rel = expr, "=="
poly = Poly(expr, gen)
if not poly.get_domain().is_Exact:
poly, exact = poly.to_exact(), False
domain = poly.get_domain()
if not (domain.is_ZZ or domain.is_QQ):
raise NotImplementedError("inequality solving is not supported over %s" % domain)
_polys.append((poly, rel))
polys.append(_polys)
solution = solve_poly_inequalities(polys)
if not exact:
solution = solution.evalf()
if not relational:
return solution
real = ask(Q.real(gen), assumptions=assume)
if not real:
result = And(solution.as_relational(re(gen)), Eq(im(gen), 0))
else:
result = solution.as_relational(gen)
return result
def test_zero_0():
z = Integer(0)
assert ask(Q.nonzero(z)) == False
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == True
assert ask(Q.rational(z)) == True
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == False
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == True
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == True
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
def test_E():
z = S.Exp1
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
def test_Rational_number():
r = Rational(3,4)
assert ask(Q.commutative(r)) == True
assert ask(Q.integer(r)) == False
assert ask(Q.rational(r)) == True
assert ask(Q.real(r)) == True
assert ask(Q.complex(r)) == True
assert ask(Q.irrational(r)) == False
assert ask(Q.imaginary(r)) == False
assert ask(Q.positive(r)) == True
assert ask(Q.negative(r)) == False
assert ask(Q.even(r)) == False
assert ask(Q.odd(r)) == False
assert ask(Q.bounded(r)) == True
assert ask(Q.infinitesimal(r)) == False
assert ask(Q.prime(r)) == False
assert ask(Q.composite(r)) == False
r = Rational(1,4)
assert ask(Q.positive(r)) == True
assert ask(Q.negative(r)) == False
r = Rational(5,4)
assert ask(Q.negative(r)) == False
assert ask(Q.positive(r)) == True
r = Rational(5,3)
assert ask(Q.positive(r)) == True
assert ask(Q.negative(r)) == False
r = Rational(-3,4)
assert ask(Q.positive(r)) == False
assert ask(Q.negative(r)) == True
r = Rational(-1,4)
assert ask(Q.positive(r)) == False
assert ask(Q.negative(r)) == True
r = Rational(-5,4)
assert ask(Q.negative(r)) == True
assert ask(Q.positive(r)) == False
r = Rational(-5,3)
assert ask(Q.positive(r)) == False
assert ask(Q.negative(r)) == True
def exp(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return True
if ask(Q.imaginary(expr.args[0]), assumptions):
from sympy import pi, I
return ask(Q.even(expr.args[0] / (I * pi)), assumptions)
def _(expr, assumptions):
if ask(Q.real(expr.exp), assumptions):
return True
if ask(Q.imaginary(expr.exp), assumptions):
return ask(Q.even(expr.exp / (I * pi)), assumptions)
def test_imaginary():
x, y, z = symbols('x,y,z')
I = S.ImaginaryUnit
assert ask(Q.imaginary(x)) == None
assert ask(Q.imaginary(x), Q.real(x)) == False
assert ask(Q.imaginary(x), Q.prime(x)) == False
assert ask(Q.imaginary(x + 1), Q.real(x)) == False
assert ask(Q.imaginary(x + 1), Q.imaginary(x)) == False
assert ask(Q.imaginary(x + I), Q.real(x)) == False
assert ask(Q.imaginary(x + I), Q.imaginary(x)) == True
assert ask(Q.imaginary(x + y), Q.imaginary(x) & Q.imaginary(y)) == True
assert ask(Q.imaginary(x + y), Q.real(x) & Q.real(y)) == False
assert ask(Q.imaginary(x + y), Q.imaginary(x) & Q.real(y)) == False
assert ask(Q.imaginary(x + y), Q.complex(x) & Q.real(y)) == None
assert ask(Q.imaginary(I * x), Q.real(x)) == True
assert ask(Q.imaginary(I * x), Q.imaginary(x)) == False
assert ask(Q.imaginary(I * x), Q.complex(x)) == None
assert ask(Q.imaginary(x * y), Q.imaginary(x) & Q.real(y)) == True
assert ask(Q.imaginary(x + y + z),
Q.real(x) & Q.real(y) & Q.real(z)) == False
assert ask(Q.imaginary(x + y + z),
Q.real(x) & Q.real(y) & Q.imaginary(z)) == None
assert ask(Q.imaginary(x + y + z),
Q.real(x) & Q.imaginary(y) & Q.imaginary(z)) == False
def get_known_facts(x=None):
"""
Facts between unary predicates.
Parameters
==========
x : Symbol, optional
Placeholder symbol for unary facts. Default is ``Symbol('x')``.
Returns
=======
fact : Known facts in conjugated normal form.
"""
if x is None:
x = Symbol('x')
fact = And(
# primitive predicates for extended real exclude each other.
Exclusive(Q.negative_infinite(x), Q.negative(x), Q.zero(x),
Q.positive(x), Q.positive_infinite(x)),
# build complex plane
Exclusive(Q.real(x), Q.imaginary(x)),
Implies(Q.real(x) | Q.imaginary(x), Q.complex(x)),
# other subsets of complex
Exclusive(Q.transcendental(x), Q.algebraic(x)),
Equivalent(Q.real(x),
Q.rational(x) | Q.irrational(x)),
Exclusive(Q.irrational(x), Q.rational(x)),
Implies(Q.rational(x), Q.algebraic(x)),
# integers
Exclusive(Q.even(x), Q.odd(x)),
Implies(Q.integer(x), Q.rational(x)),
Implies(Q.zero(x), Q.even(x)),
Exclusive(Q.composite(x), Q.prime(x)),
Implies(Q.composite(x) | Q.prime(x),
Q.integer(x) & Q.positive(x)),
Implies(Q.even(x) & Q.positive(x) & ~Q.prime(x), Q.composite(x)),
# hermitian and antihermitian
Implies(Q.real(x), Q.hermitian(x)),
Implies(Q.imaginary(x), Q.antihermitian(x)),
Implies(Q.zero(x),
Q.hermitian(x) | Q.antihermitian(x)),
# define finity and infinity, and build extended real line
Exclusive(Q.infinite(x), Q.finite(x)),
Implies(Q.complex(x), Q.finite(x)),
Implies(
Q.negative_infinite(x) | Q.positive_infinite(x), Q.infinite(x)),
# commutativity
Implies(Q.finite(x) | Q.infinite(x), Q.commutative(x)),
# matrices
Implies(Q.orthogonal(x), Q.positive_definite(x)),
Implies(Q.orthogonal(x), Q.unitary(x)),
Implies(Q.unitary(x) & Q.real_elements(x), Q.orthogonal(x)),
Implies(Q.unitary(x), Q.normal(x)),
Implies(Q.unitary(x), Q.invertible(x)),
Implies(Q.normal(x), Q.square(x)),
Implies(Q.diagonal(x), Q.normal(x)),
Implies(Q.positive_definite(x), Q.invertible(x)),
Implies(Q.diagonal(x), Q.upper_triangular(x)),
Implies(Q.diagonal(x), Q.lower_triangular(x)),
Implies(Q.lower_triangular(x), Q.triangular(x)),
Implies(Q.upper_triangular(x), Q.triangular(x)),
Implies(Q.triangular(x),
Q.upper_triangular(x) | Q.lower_triangular(x)),
Implies(Q.upper_triangular(x) & Q.lower_triangular(x), Q.diagonal(x)),
Implies(Q.diagonal(x), Q.symmetric(x)),
Implies(Q.unit_triangular(x), Q.triangular(x)),
Implies(Q.invertible(x), Q.fullrank(x)),
Implies(Q.invertible(x), Q.square(x)),
Implies(Q.symmetric(x), Q.square(x)),
Implies(Q.fullrank(x) & Q.square(x), Q.invertible(x)),
Equivalent(Q.invertible(x), ~Q.singular(x)),
Implies(Q.integer_elements(x), Q.real_elements(x)),
Implies(Q.real_elements(x), Q.complex_elements(x)),
)
return fact
def test_real():
x, y = symbols('x,y')
assert ask(Q.real(x)) == None
assert ask(Q.real(x), Q.real(x)) == True
assert ask(Q.real(x), Q.nonzero(x)) == True
assert ask(Q.real(x), Q.positive(x)) == True
assert ask(Q.real(x), Q.negative(x)) == True
assert ask(Q.real(x), Q.integer(x)) == True
assert ask(Q.real(x), Q.even(x)) == True
assert ask(Q.real(x), Q.prime(x)) == True
assert ask(Q.real(x / sqrt(2)), Q.real(x)) == True
assert ask(Q.real(x / sqrt(-2)), Q.real(x)) == False
I = S.ImaginaryUnit
assert ask(Q.real(x + 1), Q.real(x)) == True
assert ask(Q.real(x + I), Q.real(x)) == False
assert ask(Q.real(x + I), Q.complex(x)) == None
assert ask(Q.real(2 * x), Q.real(x)) == True
assert ask(Q.real(I * x), Q.real(x)) == False
assert ask(Q.real(I * x), Q.imaginary(x)) == True
assert ask(Q.real(I * x), Q.complex(x)) == None
assert ask(Q.real(x**2), Q.real(x)) == True
assert ask(Q.real(sqrt(x)), Q.negative(x)) == False
assert ask(Q.real(x**y), Q.real(x) & Q.integer(y)) == True
assert ask(Q.real(x**y), Q.real(x) & Q.real(y)) == None
assert ask(Q.real(x**y), Q.positive(x) & Q.real(y)) == True
# trigonometric functions
assert ask(Q.real(sin(x))) == None
assert ask(Q.real(cos(x))) == None
assert ask(Q.real(sin(x)), Q.real(x)) == True
assert ask(Q.real(cos(x)), Q.real(x)) == True
# exponential function
assert ask(Q.real(exp(x))) == None
assert ask(Q.real(exp(x)), Q.real(x)) == True
assert ask(Q.real(x + exp(x)), Q.real(x)) == True
# Q.complexes
assert ask(Q.real(re(x))) == True
assert ask(Q.real(im(x))) == True
def test_functions_in_assumptions():
from sympy.logic.boolalg import Equivalent, Xor
x = symbols('x')
assert ask(Q.negative(x), Q.real(x) >> Q.positive(x)) is False
assert ask(Q.negative(x), Equivalent(Q.real(x), Q.positive(x))) is False
assert ask(Q.negative(x), Xor(Q.real(x), Q.negative(x))) is False
def test_composite_ask():
x = symbols('x')
assert ask(Q.negative(x) & Q.integer(x),
assumptions=Q.real(x) >> Q.positive(x)) is False
def _(expr, assumptions):
if ask(Q.real(expr.exp), assumptions):
return True
if ask(Q.imaginary(expr.exp), assumptions):
from sympy import pi, I
return ask(Q.even(expr.exp / (I * pi)), assumptions)
def acot(expr, assumptions):
return ask(Q.real(expr.args[0]), assumptions)
def _(expr, assumptions):
"""
* Real**Integer -> Real
* Positive**Real -> Real
* Real**(Integer/Even) -> Real if base is nonnegative
* Real**(Integer/Odd) -> Real
* Imaginary**(Integer/Even) -> Real
* Imaginary**(Integer/Odd) -> not Real
* Imaginary**Real -> ? since Real could be 0 (giving real)
or 1 (giving imaginary)
* b**Imaginary -> Real if log(b) is imaginary and b != 0
and exponent != integer multiple of
I*pi/log(b)
* Real**Real -> ? e.g. sqrt(-1) is imaginary and
sqrt(2) is not
"""
if expr.is_number:
return _RealPredicate_number(expr, assumptions)
if expr.base == E:
return ask(
Q.integer(expr.exp / I / pi) | Q.real(expr.exp), assumptions)
if expr.base.func == exp or (expr.base.is_Pow and expr.base.base == E):
if ask(Q.imaginary(expr.base.exp), assumptions):
if ask(Q.imaginary(expr.exp), assumptions):
return True
# If the i = (exp's arg)/(I*pi) is an integer or half-integer
# multiple of I*pi then 2*i will be an integer. In addition,
# exp(i*I*pi) = (-1)**i so the overall realness of the expr
# can be determined by replacing exp(i*I*pi) with (-1)**i.
i = expr.base.exp / I / pi
if ask(Q.integer(2 * i), assumptions):
return ask(Q.real((S.NegativeOne**i)**expr.exp), assumptions)
return
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
odd = ask(Q.odd(expr.exp), assumptions)
if odd is not None:
return not odd
return
if ask(Q.imaginary(expr.exp), assumptions):
imlog = ask(Q.imaginary(log(expr.base)), assumptions)
if imlog is not None:
# I**i -> real, log(I) is imag;
# (2*I)**i -> complex, log(2*I) is not imag
return imlog
if ask(Q.real(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if expr.exp.is_Rational and \
ask(Q.even(expr.exp.q), assumptions):
return ask(Q.positive(expr.base), assumptions)
elif ask(Q.integer(expr.exp), assumptions):
return True
elif ask(Q.positive(expr.base), assumptions):
return True
elif ask(Q.negative(expr.base), assumptions):
return False
def sin(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return True
def reduce_abs_inequality(expr, rel, gen, assume=True):
"""Reduce an inequality with nested absolute values.
Examples
========
>>> from sympy import Q, Abs
>>> from sympy.abc import x
>>> from sympy.solvers.inequalities import reduce_abs_inequality
>>> reduce_abs_inequality(Abs(x - 5) - 3, '<', x, assume=Q.real(x))
And(2 < x, x < 8)
>>> reduce_abs_inequality(Abs(x + 2)*3 - 13, '<', x, assume=Q.real(x))
And(-19/3 < x, x < 7/3)
See Also
========
reduce_abs_inequalities
"""
if not ask(Q.real(gen), assumptions=assume):
raise NotImplementedError(
"can't solve inequalities with absolute values of a complex variable"
)
def _bottom_up_scan(expr):
exprs = []
if expr.is_Add or expr.is_Mul:
op = expr.__class__
for arg in expr.args:
_exprs = _bottom_up_scan(arg)
if not exprs:
exprs = _exprs
else:
args = []
for expr, conds in exprs:
for _expr, _conds in _exprs:
args.append((op(expr, _expr), conds + _conds))
exprs = args
elif expr.is_Pow:
n = expr.exp
if not n.is_Integer or n < 0:
raise ValueError(
"only non-negative integer powers are allowed")
_exprs = _bottom_up_scan(expr.base)
for expr, conds in _exprs:
exprs.append((expr**n, conds))
elif isinstance(expr, Abs):
_exprs = _bottom_up_scan(expr.args[0])
for expr, conds in _exprs:
exprs.append((expr, conds + [Ge(expr, 0)]))
exprs.append((-expr, conds + [Lt(expr, 0)]))
else:
exprs = [(expr, [])]
return exprs
exprs = _bottom_up_scan(expr)
mapping = {'<': '>', '<=': '>='}
inequalities = []
for expr, conds in exprs:
if rel not in mapping.keys():
expr = Relational(expr, 0, rel)
else:
expr = Relational(-expr, 0, mapping[rel])
inequalities.append([expr] + conds)
return reduce_poly_inequalities(inequalities, gen, assume)
def Basic(expr, assumptions):
return fuzzy_and([fuzzy_not(ask(Q.nonzero(expr), assumptions)),
ask(Q.real(expr), assumptions)])
def _(expr, assumptions):
return ask(Q.real(expr), assumptions)
def test_complex():
x, y = symbols('x,y')
assert ask(Q.complex(x)) == None
assert ask(Q.complex(x), Q.complex(x)) == True
assert ask(Q.complex(x), Q.complex(y)) == None
assert ask(Q.complex(x), ~Q.complex(x)) == False
assert ask(Q.complex(x), Q.real(x)) == True
assert ask(Q.complex(x), ~Q.real(x)) == None
assert ask(Q.complex(x), Q.rational(x)) == True
assert ask(Q.complex(x), Q.irrational(x)) == True
assert ask(Q.complex(x), Q.positive(x)) == True
assert ask(Q.complex(x), Q.imaginary(x)) == True
# a+b
assert ask(Q.complex(x + 1), Q.complex(x)) == True
assert ask(Q.complex(x + 1), Q.real(x)) == True
assert ask(Q.complex(x + 1), Q.rational(x)) == True
assert ask(Q.complex(x + 1), Q.irrational(x)) == True
assert ask(Q.complex(x + 1), Q.imaginary(x)) == True
assert ask(Q.complex(x + 1), Q.integer(x)) == True
assert ask(Q.complex(x + 1), Q.even(x)) == True
assert ask(Q.complex(x + 1), Q.odd(x)) == True
assert ask(Q.complex(x + y), Q.complex(x) & Q.complex(y)) == True
assert ask(Q.complex(x + y), Q.real(x) & Q.imaginary(y)) == True
# a*x +b
assert ask(Q.complex(2 * x + 1), Q.complex(x)) == True
assert ask(Q.complex(2 * x + 1), Q.real(x)) == True
assert ask(Q.complex(2 * x + 1), Q.positive(x)) == True
assert ask(Q.complex(2 * x + 1), Q.rational(x)) == True
assert ask(Q.complex(2 * x + 1), Q.irrational(x)) == True
assert ask(Q.complex(2 * x + 1), Q.imaginary(x)) == True
assert ask(Q.complex(2 * x + 1), Q.integer(x)) == True
assert ask(Q.complex(2 * x + 1), Q.even(x)) == True
assert ask(Q.complex(2 * x + 1), Q.odd(x)) == True
# x**2
assert ask(Q.complex(x**2), Q.complex(x)) == True
assert ask(Q.complex(x**2), Q.real(x)) == True
assert ask(Q.complex(x**2), Q.positive(x)) == True
assert ask(Q.complex(x**2), Q.rational(x)) == True
assert ask(Q.complex(x**2), Q.irrational(x)) == True
assert ask(Q.complex(x**2), Q.imaginary(x)) == True
assert ask(Q.complex(x**2), Q.integer(x)) == True
assert ask(Q.complex(x**2), Q.even(x)) == True
assert ask(Q.complex(x**2), Q.odd(x)) == True
# 2**x
assert ask(Q.complex(2**x), Q.complex(x)) == True
assert ask(Q.complex(2**x), Q.real(x)) == True
assert ask(Q.complex(2**x), Q.positive(x)) == True
assert ask(Q.complex(2**x), Q.rational(x)) == True
assert ask(Q.complex(2**x), Q.irrational(x)) == True
assert ask(Q.complex(2**x), Q.imaginary(x)) == True
assert ask(Q.complex(2**x), Q.integer(x)) == True
assert ask(Q.complex(2**x), Q.even(x)) == True
assert ask(Q.complex(2**x), Q.odd(x)) == True
assert ask(Q.complex(x**y), Q.complex(x) & Q.complex(y)) == True
# trigonometric expressions
assert ask(Q.complex(sin(x))) == True
assert ask(Q.complex(sin(2 * x + 1))) == True
assert ask(Q.complex(cos(x))) == True
assert ask(Q.complex(cos(2 * x + 1))) == True
# exponential
assert ask(Q.complex(exp(x))) == True
assert ask(Q.complex(exp(x))) == True
# Q.complexes
assert ask(Q.complex(Abs(x))) == True
assert ask(Q.complex(re(x))) == True
assert ask(Q.complex(im(x))) == True
def exp(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return False
def _(expr, assumptions):
if ask(Q.real(expr.exp), assumptions):
return False
def exp(expr, assumptions):
return ask(
Q.integer(expr.args[0] / I / pi) | Q.real(expr.args[0]),
assumptions)
def _(expr, assumptions):
if isinstance(expr, MatrixBase):
return None
return ask(Q.real(expr), assumptions)
def test_positive_xfail():
assert ask(Q.positive(1 / (1 + x**2)), Q.real(x)) == True
def exp(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return True
if ask(Q.imaginary(expr.args[0]), assumptions):
return False
def refine_Pow(expr, assumptions):
"""
Handler for instances of Pow.
>>> from sympy import Symbol, Q
>>> from sympy.assumptions.refine import refine_Pow
>>> from sympy.abc import x,y,z
>>> refine_Pow((-1)**x, Q.real(x))
>>> refine_Pow((-1)**x, Q.even(x))
1
>>> refine_Pow((-1)**x, Q.odd(x))
-1
For powers of -1, even parts of the exponent can be simplified:
>>> refine_Pow((-1)**(x+y), Q.even(x))
(-1)**y
>>> refine_Pow((-1)**(x+y+z), Q.odd(x) & Q.odd(z))
(-1)**y
>>> refine_Pow((-1)**(x+y+2), Q.odd(x))
(-1)**(y + 1)
>>> refine_Pow((-1)**(x+3), True)
(-1)**(x + 1)
"""
from sympy.core import Pow, Rational
from sympy.functions.elementary.complexes import Abs
from sympy.functions import sign
if isinstance(expr.base, Abs):
if ask(Q.real(expr.base.args[0]), assumptions) and \
ask(Q.even(expr.exp), assumptions):
return expr.base.args[0]**expr.exp
if ask(Q.real(expr.base), assumptions):
if expr.base.is_number:
if ask(Q.even(expr.exp), assumptions):
return abs(expr.base)**expr.exp
if ask(Q.odd(expr.exp), assumptions):
return sign(expr.base) * abs(expr.base)**expr.exp
if isinstance(expr.exp, Rational):
if type(expr.base) is Pow:
return abs(expr.base.base)**(expr.base.exp * expr.exp)
if expr.base is S.NegativeOne:
if expr.exp.is_Add:
old = expr
# For powers of (-1) we can remove
# - even terms
# - pairs of odd terms
# - a single odd term + 1
# - A numerical constant N can be replaced with mod(N,2)
coeff, terms = expr.exp.as_coeff_add()
terms = set(terms)
even_terms = set([])
odd_terms = set([])
initial_number_of_terms = len(terms)
for t in terms:
if ask(Q.even(t), assumptions):
even_terms.add(t)
elif ask(Q.odd(t), assumptions):
odd_terms.add(t)
terms -= even_terms
if len(odd_terms) % 2:
terms -= odd_terms
new_coeff = (coeff + S.One) % 2
else:
terms -= odd_terms
new_coeff = coeff % 2
if new_coeff != coeff or len(terms) < initial_number_of_terms:
terms.add(new_coeff)
expr = expr.base**(Add(*terms))
# Handle (-1)**((-1)**n/2 + m/2)
e2 = 2 * expr.exp
if ask(Q.even(e2), assumptions):
if e2.could_extract_minus_sign():
e2 *= expr.base
if e2.is_Add:
i, p = e2.as_two_terms()
if p.is_Pow and p.base is S.NegativeOne:
if ask(Q.integer(p.exp), assumptions):
i = (i + 1) / 2
if ask(Q.even(i), assumptions):
return expr.base**p.exp
elif ask(Q.odd(i), assumptions):
return expr.base**(p.exp + 1)
else:
return expr.base**(p.exp + i)
if old != expr:
return expr
def reduce_rational_inequalities(exprs, gen, assume=True, relational=True):
"""Reduce a system of rational inequalities with rational coefficients.
Examples
========
>>> from sympy import Poly, Symbol
>>> from sympy.solvers.inequalities import reduce_rational_inequalities
>>> x = Symbol('x', real=True)
>>> reduce_rational_inequalities([[x**2 <= 0]], x)
x == 0
>>> reduce_rational_inequalities([[x + 2 > 0]], x)
x > -2
>>> reduce_rational_inequalities([[(x + 2, ">")]], x)
x > -2
>>> reduce_rational_inequalities([[x + 2]], x)
x == -2
"""
exact = True
eqs = []
for _exprs in exprs:
_eqs = []
for expr in _exprs:
if isinstance(expr, tuple):
expr, rel = expr
else:
if expr.is_Relational:
expr, rel = expr.lhs - expr.rhs, expr.rel_op
else:
expr, rel = expr, '=='
try:
(numer, denom), opt = parallel_poly_from_expr(
expr.together().as_numer_denom(), gen)
except PolynomialError:
raise PolynomialError(
"only polynomials and "
"rational functions are supported in this context")
if not opt.domain.is_Exact:
numer, denom, exact = numer.to_exact(), denom.to_exact(), False
domain = opt.domain.get_exact()
if not (domain.is_ZZ or domain.is_QQ):
raise NotImplementedError(
"inequality solving is not supported over %s" % opt.domain)
_eqs.append(((numer, denom), rel))
eqs.append(_eqs)
solution = solve_rational_inequalities(eqs)
if not exact:
solution = solution.evalf()
if not relational:
return solution
real = ask(Q.real(gen), assumptions=assume)
if not real:
result = And(solution.as_relational(re(gen)), Eq(im(gen), 0))
else:
result = solution.as_relational(gen)
return result
def _(expr, assumptions):
if ask(Q.real(expr.exp), assumptions):
return False
raise MDNotImplementedError
def re(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return ask(Q.even(expr.args[0]), assumptions)
def test_pi():
z = S.Pi
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
z = S.Pi + 1
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
z = 2 * S.Pi
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
z = S.Pi**2
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
z = (1 + S.Pi)**2
assert ask(Q.commutative(z)) == True
assert ask(Q.integer(z)) == False
assert ask(Q.rational(z)) == False
assert ask(Q.real(z)) == True
assert ask(Q.complex(z)) == True
assert ask(Q.irrational(z)) == True
assert ask(Q.imaginary(z)) == False
assert ask(Q.positive(z)) == True
assert ask(Q.negative(z)) == False
assert ask(Q.even(z)) == False
assert ask(Q.odd(z)) == False
assert ask(Q.bounded(z)) == True
assert ask(Q.infinitesimal(z)) == False
assert ask(Q.prime(z)) == False
assert ask(Q.composite(z)) == False
def refine_Pow(expr, assumptions):
"""
Handler for instances of Pow.
>>> from sympy import Symbol, Q
>>> from sympy.assumptions.refine import refine_Pow
>>> from sympy.abc import x,y,z
>>> refine_Pow((-1)**x, Q.real(x))
>>> refine_Pow((-1)**x, Q.even(x))
1
>>> refine_Pow((-1)**x, Q.odd(x))
-1
For powers of -1, even parts of the exponent can be simplified:
>>> refine_Pow((-1)**(x+y), Q.even(x))
(-1)**y
>>> refine_Pow((-1)**(x+y+z), Q.odd(x) & Q.odd(z))
(-1)**y
>>> refine_Pow((-1)**(x+y+2), Q.odd(x))
(-1)**(y + 1)
>>> refine_Pow((-1)**(x+3), True)
(-1)**(x + 1)
"""
from sympy.core import Pow, Rational
from sympy.functions import sign
if ask(Q.real(expr.base), assumptions):
if expr.base.is_number:
if ask(Q.even(expr.exp), assumptions):
return abs(expr.base) ** expr.exp
if ask(Q.odd(expr.exp), assumptions):
return sign(expr.base) * abs(expr.base) ** expr.exp
if isinstance(expr.exp, Rational):
if type(expr.base) is Pow:
return abs(expr.base.base) ** (expr.base.exp * expr.exp)
if expr.base is S.NegativeOne:
if expr.exp.is_Add:
# For powers of (-1) we can remove
# - even terms
# - pairs of odd terms
# - a single odd term + 1
# - A numerical constant N can be replaced with mod(N,2)
coeff, terms = expr.exp.as_coeff_add()
terms = set(terms)
even_terms = set([])
odd_terms = set([])
initial_number_of_terms = len(terms)
for t in terms:
if ask(Q.even(t), assumptions):
even_terms.add(t)
elif ask(Q.odd(t), assumptions):
odd_terms.add(t)
terms -= even_terms
if len(odd_terms) % 2:
terms -= odd_terms
new_coeff = (coeff + S.One) % 2
else:
terms -= odd_terms
new_coeff = coeff % 2
if new_coeff != coeff or len(terms) < initial_number_of_terms:
terms.add(new_coeff)
return expr.base**(Add(*terms))
def reduce_poly_inequalities(exprs, gen, assume=True, relational=True):
"""Reduce a system of polynomial inequalities with rational coefficients.
Examples
========
>>> from sympy import Poly, Symbol
>>> from sympy.solvers.inequalities import reduce_poly_inequalities
>>> x = Symbol('x', real=True)
>>> reduce_poly_inequalities([[x**2 <= 0]], x)
x == 0
>>> reduce_poly_inequalities([[x + 2 > 0]], x)
-2 < x
"""
exact = True
polys = []
for _exprs in exprs:
_polys = []
for expr in _exprs:
if isinstance(expr, tuple):
expr, rel = expr
else:
if expr.is_Relational:
expr, rel = expr.lhs - expr.rhs, expr.rel_op
else:
expr, rel = expr, '=='
poly = Poly(expr, gen)
if not poly.get_domain().is_Exact:
poly, exact = poly.to_exact(), False
domain = poly.get_domain()
if not (domain.is_ZZ or domain.is_QQ):
raise NotImplementedError(
"inequality solving is not supported over %s" % domain)
_polys.append((poly, rel))
polys.append(_polys)
solution = solve_poly_inequalities(polys)
if not exact:
solution = solution.evalf()
if not relational:
return solution
real = ask(Q.real(gen), assumptions=assume)
if not real:
result = And(solution.as_relational(re(gen)), Eq(im(gen), 0))
else:
result = solution.as_relational(gen)
return result
def _(expr, assumptions):
return ask(Q.integer(expr.exp / I / pi) | Q.real(expr.exp), assumptions)
