"""
Handlers for predicates related to set membership: integer, rational, etc.
"""
from __future__ import print_function, division
from sympy.assumptions import Q, ask
from sympy.assumptions.handlers import CommonHandler, test_closed_group
from sympy.core.numbers import pi
from sympy.functions.elementary.exponential import exp, log
from sympy import I
[docs]class AskIntegerHandler(CommonHandler):
"""
Handler for Q.integer
Test that an expression belongs to the field of integer numbers
"""
@staticmethod
def Expr(expr, assumptions):
return expr.is_integer
@staticmethod
def _number(expr, assumptions):
# helper method
try:
i = int(expr.round())
if not (expr - i).equals(0):
raise TypeError
return True
except TypeError:
return False
[docs] @staticmethod
def Add(expr, assumptions):
"""
Integer + Integer -> Integer
Integer + !Integer -> !Integer
!Integer + !Integer -> ?
"""
if expr.is_number:
return AskIntegerHandler._number(expr, assumptions)
return test_closed_group(expr, assumptions, Q.integer)
[docs] @staticmethod
def Mul(expr, assumptions):
"""
Integer*Integer -> Integer
Integer*Irrational -> !Integer
Odd/Even -> !Integer
Integer*Rational -> ?
"""
if expr.is_number:
return AskIntegerHandler._number(expr, assumptions)
_output = True
for arg in expr.args:
if not ask(Q.integer(arg), assumptions):
if arg.is_Rational:
if arg.q == 2:
return ask(Q.even(2*expr), assumptions)
if ~(arg.q & 1):
return None
elif ask(Q.irrational(arg), assumptions):
if _output:
_output = False
else:
return
else:
return
else:
return _output
Pow = Add
int, Integer = [staticmethod(CommonHandler.AlwaysTrue)]*2
Pi, Exp1, GoldenRatio, TribonacciConstant, Infinity, NegativeInfinity, ImaginaryUnit = \
[staticmethod(CommonHandler.AlwaysFalse)]*7
@staticmethod
def Rational(expr, assumptions):
# rationals with denominator one get
# evaluated to Integers
return False
@staticmethod
def Abs(expr, assumptions):
return ask(Q.integer(expr.args[0]), assumptions)
@staticmethod
def MatrixElement(expr, assumptions):
return ask(Q.integer_elements(expr.args[0]), assumptions)
Determinant = Trace = MatrixElement
[docs]class AskRationalHandler(CommonHandler):
"""
Handler for Q.rational
Test that an expression belongs to the field of rational numbers
"""
@staticmethod
def Expr(expr, assumptions):
return expr.is_rational
[docs] @staticmethod
def Add(expr, assumptions):
"""
Rational + Rational -> Rational
Rational + !Rational -> !Rational
!Rational + !Rational -> ?
"""
if expr.is_number:
if expr.as_real_imag()[1]:
return False
return test_closed_group(expr, assumptions, Q.rational)
Mul = Add
[docs] @staticmethod
def Pow(expr, assumptions):
"""
Rational ** Integer -> Rational
Irrational ** Rational -> Irrational
Rational ** Irrational -> ?
"""
if ask(Q.integer(expr.exp), assumptions):
return ask(Q.rational(expr.base), assumptions)
elif ask(Q.rational(expr.exp), assumptions):
if ask(Q.prime(expr.base), assumptions):
return False
Rational = staticmethod(CommonHandler.AlwaysTrue)
Float = staticmethod(CommonHandler.AlwaysNone)
ImaginaryUnit, Infinity, NegativeInfinity, Pi, Exp1, GoldenRatio, TribonacciConstant = \
[staticmethod(CommonHandler.AlwaysFalse)]*7
@staticmethod
def exp(expr, assumptions):
x = expr.args[0]
if ask(Q.rational(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
@staticmethod
def cot(expr, assumptions):
x = expr.args[0]
if ask(Q.rational(x), assumptions):
return False
@staticmethod
def log(expr, assumptions):
x = expr.args[0]
if ask(Q.rational(x), assumptions):
return ask(~Q.nonzero(x - 1), assumptions)
sin, cos, tan, asin, atan = [exp]*5
acos, acot = log, cot
class AskIrrationalHandler(CommonHandler):
@staticmethod
def Expr(expr, assumptions):
return expr.is_irrational
@staticmethod
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
[docs]class AskRealHandler(CommonHandler):
"""
Handler for Q.real
Test that an expression belongs to the field of real numbers
"""
@staticmethod
def Expr(expr, assumptions):
return expr.is_real
@staticmethod
def _number(expr, assumptions):
# let as_real_imag() work first since the expression may
# be simpler to evaluate
i = expr.as_real_imag()[1].evalf(2)
if i._prec != 1:
return not i
# allow None to be returned if we couldn't show for sure
# that i was 0
[docs] @staticmethod
def Add(expr, assumptions):
"""
Real + Real -> Real
Real + (Complex & !Real) -> !Real
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
return test_closed_group(expr, assumptions, Q.real)
[docs] @staticmethod
def Mul(expr, assumptions):
"""
Real*Real -> Real
Real*Imaginary -> !Real
Imaginary*Imaginary -> Real
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
result = True
for arg in expr.args:
if ask(Q.real(arg), assumptions):
pass
elif ask(Q.imaginary(arg), assumptions):
result = result ^ True
else:
break
else:
return result
[docs] @staticmethod
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
Rational, Float, Pi, Exp1, GoldenRatio, TribonacciConstant, Abs, re, im = \
[staticmethod(CommonHandler.AlwaysTrue)]*9
ImaginaryUnit, Infinity, NegativeInfinity = \
[staticmethod(CommonHandler.AlwaysFalse)]*3
@staticmethod
def sin(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return True
cos = sin
@staticmethod
def exp(expr, assumptions):
return ask(Q.integer(expr.args[0]/I/pi) | Q.real(expr.args[0]), assumptions)
@staticmethod
def log(expr, assumptions):
return ask(Q.positive(expr.args[0]), assumptions)
@staticmethod
def MatrixElement(expr, assumptions):
return ask(Q.real_elements(expr.args[0]), assumptions)
Determinant = Trace = MatrixElement
[docs]class AskExtendedRealHandler(AskRealHandler):
"""
Handler for Q.extended_real
Test that an expression belongs to the field of extended real numbers,
that is real numbers union {Infinity, -Infinity}
"""
@staticmethod
def Add(expr, assumptions):
return test_closed_group(expr, assumptions, Q.extended_real)
Mul, Pow = [Add]*2
Infinity, NegativeInfinity = [staticmethod(CommonHandler.AlwaysTrue)]*2
[docs]class AskHermitianHandler(AskRealHandler):
"""
Handler for Q.hermitian
Test that an expression belongs to the field of Hermitian operators
"""
[docs] @staticmethod
def Add(expr, assumptions):
"""
Hermitian + Hermitian -> Hermitian
Hermitian + !Hermitian -> !Hermitian
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
return test_closed_group(expr, assumptions, Q.hermitian)
[docs] @staticmethod
def Mul(expr, assumptions):
"""
As long as there is at most only one noncommutative term:
Hermitian*Hermitian -> Hermitian
Hermitian*Antihermitian -> !Hermitian
Antihermitian*Antihermitian -> Hermitian
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
nccount = 0
result = True
for arg in expr.args:
if ask(Q.antihermitian(arg), assumptions):
result = result ^ True
elif not ask(Q.hermitian(arg), assumptions):
break
if ask(~Q.commutative(arg), assumptions):
nccount += 1
if nccount > 1:
break
else:
return result
[docs] @staticmethod
def Pow(expr, assumptions):
"""
Hermitian**Integer -> Hermitian
"""
if expr.is_number:
return AskRealHandler._number(expr, assumptions)
if ask(Q.hermitian(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
return True
@staticmethod
def sin(expr, assumptions):
if ask(Q.hermitian(expr.args[0]), assumptions):
return True
cos, exp = [sin]*2
[docs]class AskComplexHandler(CommonHandler):
"""
Handler for Q.complex
Test that an expression belongs to the field of complex numbers
"""
@staticmethod
def Expr(expr, assumptions):
return expr.is_complex
@staticmethod
def Add(expr, assumptions):
return test_closed_group(expr, assumptions, Q.complex)
Mul, Pow = [Add]*2
Number, sin, cos, log, exp, re, im, NumberSymbol, Abs, ImaginaryUnit = \
[staticmethod(CommonHandler.AlwaysTrue)]*10 # they are all complex functions or expressions
Infinity, NegativeInfinity = [staticmethod(CommonHandler.AlwaysFalse)]*2
@staticmethod
def MatrixElement(expr, assumptions):
return ask(Q.complex_elements(expr.args[0]), assumptions)
Determinant = Trace = MatrixElement
[docs]class AskImaginaryHandler(CommonHandler):
"""
Handler for Q.imaginary
Test that an expression belongs to the field of imaginary numbers,
that is, numbers in the form x*I, where x is real
"""
@staticmethod
def Expr(expr, assumptions):
return expr.is_imaginary
@staticmethod
def _number(expr, assumptions):
# let as_real_imag() work first since the expression may
# be simpler to evaluate
r = expr.as_real_imag()[0].evalf(2)
if r._prec != 1:
return not r
# allow None to be returned if we couldn't show for sure
# that r was 0
[docs] @staticmethod
def Add(expr, assumptions):
"""
Imaginary + Imaginary -> Imaginary
Imaginary + Complex -> ?
Imaginary + Real -> !Imaginary
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
reals = 0
for arg in expr.args:
if ask(Q.imaginary(arg), assumptions):
pass
elif ask(Q.real(arg), assumptions):
reals += 1
else:
break
else:
if reals == 0:
return True
if reals == 1 or (len(expr.args) == reals):
# two reals could sum 0 thus giving an imaginary
return False
[docs] @staticmethod
def Mul(expr, assumptions):
"""
Real*Imaginary -> Imaginary
Imaginary*Imaginary -> Real
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
result = False
reals = 0
for arg in expr.args:
if ask(Q.imaginary(arg), assumptions):
result = result ^ True
elif not ask(Q.real(arg), assumptions):
break
else:
if reals == len(expr.args):
return False
return result
[docs] @staticmethod
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
@staticmethod
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
@staticmethod
def exp(expr, assumptions):
a = expr.args[0]/I/pi
return ask(Q.integer(2*a) & ~Q.integer(a), assumptions)
@staticmethod
def Number(expr, assumptions):
return not (expr.as_real_imag()[1] == 0)
NumberSymbol = Number
ImaginaryUnit = staticmethod(CommonHandler.AlwaysTrue)
[docs]class AskAntiHermitianHandler(AskImaginaryHandler):
"""
Handler for Q.antihermitian
Test that an expression belongs to the field of anti-Hermitian operators,
that is, operators in the form x*I, where x is Hermitian
"""
[docs] @staticmethod
def Add(expr, assumptions):
"""
Antihermitian + Antihermitian -> Antihermitian
Antihermitian + !Antihermitian -> !Antihermitian
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
return test_closed_group(expr, assumptions, Q.antihermitian)
[docs] @staticmethod
def Mul(expr, assumptions):
"""
As long as there is at most only one noncommutative term:
Hermitian*Hermitian -> !Antihermitian
Hermitian*Antihermitian -> Antihermitian
Antihermitian*Antihermitian -> !Antihermitian
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
nccount = 0
result = False
for arg in expr.args:
if ask(Q.antihermitian(arg), assumptions):
result = result ^ True
elif not ask(Q.hermitian(arg), assumptions):
break
if ask(~Q.commutative(arg), assumptions):
nccount += 1
if nccount > 1:
break
else:
return result
[docs] @staticmethod
def Pow(expr, assumptions):
"""
Hermitian**Integer -> !Antihermitian
Antihermitian**Even -> !Antihermitian
Antihermitian**Odd -> Antihermitian
"""
if expr.is_number:
return AskImaginaryHandler._number(expr, assumptions)
if ask(Q.hermitian(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
return False
elif ask(Q.antihermitian(expr.base), assumptions):
if ask(Q.even(expr.exp), assumptions):
return False
elif ask(Q.odd(expr.exp), assumptions):
return True
[docs]class AskAlgebraicHandler(CommonHandler):
"""Handler for Q.algebraic key. """
@staticmethod
def Add(expr, assumptions):
return test_closed_group(expr, assumptions, Q.algebraic)
@staticmethod
def Mul(expr, assumptions):
return test_closed_group(expr, assumptions, Q.algebraic)
@staticmethod
def Pow(expr, assumptions):
return expr.exp.is_Rational and ask(
Q.algebraic(expr.base), assumptions)
@staticmethod
def Rational(expr, assumptions):
return expr.q != 0
Float, GoldenRatio, TribonacciConstant, ImaginaryUnit, AlgebraicNumber = \
[staticmethod(CommonHandler.AlwaysTrue)]*5
Infinity, NegativeInfinity, ComplexInfinity, Pi, Exp1 = \
[staticmethod(CommonHandler.AlwaysFalse)]*5
@staticmethod
def exp(expr, assumptions):
x = expr.args[0]
if ask(Q.algebraic(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
@staticmethod
def cot(expr, assumptions):
x = expr.args[0]
if ask(Q.algebraic(x), assumptions):
return False
@staticmethod
def log(expr, assumptions):
x = expr.args[0]
if ask(Q.algebraic(x), assumptions):
return ask(~Q.nonzero(x - 1), assumptions)
sin, cos, tan, asin, atan = [exp]*5
acos, acot = log, cot
