def test_issue_7535():
assert limit(tan(x)/sin(tan(x)), x, pi/2) == Limit(tan(x)/sin(tan(x)), x, pi/2, dir='+')
assert limit(tan(x)/sin(tan(x)), x, pi/2, dir='-') == Limit(tan(x)/sin(tan(x)), x, pi/2, dir='-')
assert limit(tan(x)/sin(tan(x)), x, pi/2, dir='+-') == Limit(tan(x)/sin(tan(x)), x, pi/2, dir='+-')
assert limit(sin(tan(x)),x,pi/2) == AccumBounds(-1, 1)
assert -oo*(1/sin(-oo)) == AccumBounds(-oo, oo)
assert oo*(1/sin(oo)) == AccumBounds(-oo, oo)
assert oo*(1/sin(-oo)) == AccumBounds(-oo, oo)
assert -oo*(1/sin(oo)) == AccumBounds(-oo, oo)
def test_issue_19770():
m = Symbol('m')
# the result is not 0 for non-real m
assert limit(cos(m*x)/x, x, oo) == Limit(cos(m*x)/x, x, oo, dir='-')
m = Symbol('m', real=True)
# can be improved to give the correct result 0
assert limit(cos(m*x)/x, x, oo) == Limit(cos(m*x)/x, x, oo, dir='-')
m = Symbol('m', nonzero=True)
assert limit(cos(m*x), x, oo) == AccumBounds(-1, 1)
assert limit(cos(m*x)/x, x, oo) == 0
def test_issue_18473():
assert limit(sin(x)**(1/x), x, oo) == Limit(sin(x)**(1/x), x, oo, dir='-')
assert limit(cos(x)**(1/x), x, oo) == Limit(cos(x)**(1/x), x, oo, dir='-')
assert limit(tan(x)**(1/x), x, oo) == Limit(tan(x)**(1/x), x, oo, dir='-')
assert limit((cos(x) + 2)**(1/x), x, oo) == 1
assert limit((sin(x) + 10)**(1/x), x, oo) == 1
assert limit((cos(x) - 2)**(1/x), x, oo) == Limit((cos(x) - 2)**(1/x), x, oo, dir='-')
assert limit((cos(x) + 1)**(1/x), x, oo) == AccumBounds(0, 1)
assert limit((tan(x)**2)**(2/x) , x, oo) == AccumBounds(0, oo)
assert limit((sin(x)**2)**(1/x), x, oo) == AccumBounds(0, 1)
def test_basic5():
class my(Function):
@classmethod
def eval(cls, arg):
if arg is S.Infinity:
return S.NaN
assert limit(my(x), x, oo) == Limit(my(x), x, oo)
def test_Rational():
n1 = Rational(1, 4)
n2 = Rational(1, 3)
n3 = Rational(2, 4)
n4 = Rational(2, -4)
n5 = Rational(0)
n7 = Rational(3)
n8 = Rational(-3)
assert str(n1*n2) == "1/12"
assert str(n1*n2) == "1/12"
assert str(n3) == "1/2"
assert str(n1*n3) == "1/8"
assert str(n1 + n3) == "3/4"
assert str(n1 + n2) == "7/12"
assert str(n1 + n4) == "-1/4"
assert str(n4*n4) == "1/4"
assert str(n4 + n2) == "-1/6"
assert str(n4 + n5) == "-1/2"
assert str(n4*n5) == "0"
assert str(n3 + n4) == "0"
assert str(n1**n7) == "1/64"
assert str(n2**n7) == "1/27"
assert str(n2**n8) == "27"
assert str(n7**n8) == "1/27"
assert str(Rational("-25")) == "-25"
assert str(Rational("1.25")) == "5/4"
assert str(Rational("-2.6e-2")) == "-13/500"
assert str(S("25/7")) == "25/7"
assert str(S("-123/569")) == "-123/569"
assert str(S("0.1[23]", rational=1)) == "61/495"
assert str(S("5.1[666]", rational=1)) == "31/6"
assert str(S("-5.1[666]", rational=1)) == "-31/6"
assert str(S("0.[9]", rational=1)) == "1"
assert str(S("-0.[9]", rational=1)) == "-1"
assert str(sqrt(Rational(1, 4))) == "1/2"
assert str(sqrt(Rational(1, 36))) == "1/6"
assert str((123**25) ** Rational(1, 25)) == "123"
assert str((123**25 + 1)**Rational(1, 25)) != "123"
assert str((123**25 - 1)**Rational(1, 25)) != "123"
assert str((123**25 - 1)**Rational(1, 25)) != "122"
assert str(sqrt(Rational(81, 36))**3) == "27/8"
assert str(1/sqrt(Rational(81, 36))**3) == "8/27"
assert str(sqrt(-4)) == str(2*I)
assert str(2**Rational(1, 10**10)) == "2**(1/10000000000)"
assert sstr(Rational(2, 3), sympy_integers=True) == "S(2)/3"
x = Symbol("x")
assert sstr(x**Rational(2, 3), sympy_integers=True) == "x**(S(2)/3)"
assert sstr(Eq(x, Rational(2, 3)), sympy_integers=True) == "Eq(x, S(2)/3)"
assert sstr(Limit(x, x, Rational(7, 2)), sympy_integers=True) == \
"Limit(x, x, S(7)/2)"
def prove(Eq):
n = Symbol.n(integer=True, positive=True)
Eq << apply(n)
x = Symbol.x(real=True)
x0 = Symbol.x0(real=True, positive=True)
Eq.continuity = Equality(Limit(1 / x, x, x0, "+-"), 1 / x0, plausible=True)
Eq << Eq.continuity.this.lhs.doit()
k, *ab = Eq[-1].lhs.args[0].args[-1].limits[0]
k = k.copy(domain=Interval(*ab, integer=True))
Eq << Eq.continuity.forall((x0, k, k + 1))
Eq.mean_value_theorem = axiom.calculus.integral.mean_value_theorem.apply(
Eq[-1])
Eq << Eq[-1].limits_assertion()
Eq << Eq[-1].inverse().split()
Eq << (Eq.mean_value_theorem.subs(
Eq[-1]), Eq.mean_value_theorem.subs(Eq[-2]))
Eq << (Eq[-1].sum((k, 1, n - 1)), Eq[-2].sum((k, 1, n)))
Eq << (Eq[-1].this.lhs.doit(), Eq[-2].this.lhs.doit().reversed)
k = Eq[-1].lhs.variable
Eq << Eq[-1].this.lhs.limits_subs(k, k - 1) + 1
assert Eq[-3].lhs > 0
Eq << (Eq[-3] / Eq[-3].lhs, Eq[-1] / Eq[-3].lhs)
Eq << (Eq[-2].limit(n, oo), Eq[-1].limit(n, oo))
Eq << Eq[-1].subs(Eq[-2])
def test_issue_17325():
assert Limit(sin(x)/x, x, 0, dir="+-").doit() == 1
assert Limit(x**2, x, 0, dir="+-").doit() == 0
assert Limit(1/x**2, x, 0, dir="+-").doit() is oo
assert Limit(1/x, x, 0, dir="+-").doit() is zoo
def test_issue_14456():
raises(NotImplementedError, lambda: Limit(exp(x), x, zoo).doit())
raises(NotImplementedError, lambda: Limit(x**2/(x+1), x, zoo).doit())
def test_issue_9205():
x, y, a = symbols('x, y, a')
assert Limit(x, x, a).free_symbols == {a}
assert Limit(x, x, a, '-').free_symbols == {a}
assert Limit(x + y, x + y, a).free_symbols == {a}
assert Limit(-x**2 + y, x**2, a).free_symbols == {y, a}
def test_Limit_dir():
raises(TypeError, lambda: Limit(x, x, 0, dir=0))
raises(ValueError, lambda: Limit(x, x, 0, dir='0'))
def test_extended_real_line():
assert limit(x - oo, x, oo) == Limit(x - oo, x, oo)
assert limit(1/(x + sin(x)) - oo, x, 0) == Limit(1/(x + sin(x)) - oo, x, 0)
assert limit(oo/x, x, oo) == Limit(oo/x, x, oo)
assert limit(x - oo + 1/x, x, oo) == Limit(x - oo + 1/x, x, oo)
def test_doit2():
f = Integral(2 * x, x)
l = Limit(f, x, oo)
# limit() breaks on the contained Integral.
assert l.doit(deep=False) == l
def apply(n):
k = Symbol.k(integer=True)
return Equality(Limit(Sum[k:1:n](1 / k) / log(n + 1), n, oo), 1)
def _limit_inf(expr, n):
try:
return Limit(expr, n, S.Infinity).doit(deep=False)
except (NotImplementedError, PoleError):
return None
def test_sympy__series__limits__Limit():
from sympy.series.limits import Limit
assert _test_args(Limit(x, x, 0, dir='-'))
def test_issue_18442():
assert limit(tan(x)**(2**(sqrt(pi))), x, oo, dir='-') == Limit(tan(x)**(2**(sqrt(pi))), x, oo, dir='-')
def contains(self, expr):
r"""
Return True if expr belongs to Order(self.expr, \*self.variables).
Return False if self belongs to expr.
Return None if the inclusion relation cannot be determined
(e.g. when self and expr have different symbols).
"""
from sympy import powsimp
if expr is S.Zero:
return True
if expr is S.NaN:
return False
if expr.is_Order:
if (not all(p == expr.point[0] for p in expr.point)
and not all(p == self.point[0]
for p in self.point)): # pragma: no cover
raise NotImplementedError(
'Order at points other than 0 '
'or oo not supported, got %s as a point.' % point)
else:
# self and/or expr is O(1):
if any(not p for p in [expr.point, self.point]):
point = self.point + expr.point
if point:
point = point[0]
else:
point = S.Zero
else:
point = self.point[0]
if expr.expr == self.expr:
# O(1) + O(1), O(1) + O(1, x), etc.
return all([x in self.args[1:] for x in expr.args[1:]])
if expr.expr.is_Add:
return all([self.contains(x) for x in expr.expr.args])
if self.expr.is_Add and point == S.Zero:
return any([
self.func(x, *self.args[1:]).contains(expr)
for x in self.expr.args
])
if self.variables and expr.variables:
common_symbols = tuple(
[s for s in self.variables if s in expr.variables])
elif self.variables:
common_symbols = self.variables
else:
common_symbols = expr.variables
if not common_symbols:
return None
if (self.expr.is_Pow and self.expr.base.is_symbol
and self.expr.exp.is_positive):
if expr.expr.is_Pow and self.expr.base == expr.expr.base:
return not (self.expr.exp - expr.expr.exp).is_positive
if expr.expr.is_Mul:
for arg in expr.expr.args:
if (arg.is_Pow and self.expr.base == arg.base
and (expr.expr / arg).is_number):
r = (self.expr.exp - arg.exp).is_positive
if not (r is None):
return not r
r = None
ratio = self.expr / expr.expr
ratio = powsimp(ratio, deep=True, combine='exp')
for s in common_symbols:
from sympy.series.limits import Limit
l = Limit(ratio, s, point).doit(heuristics=False)
if not isinstance(l, Limit):
l = l != 0
else:
l = None
if r is None:
r = l
else:
if r != l:
return
return r
if (self.expr.is_Pow and self.expr.base.is_symbol
and self.expr.exp.is_positive):
if expr.is_Pow and self.expr.base == expr.base:
return not (self.expr.exp - expr.exp).is_positive
if expr.is_Mul:
for arg in expr.args:
if (arg.is_Pow and self.expr.base == arg.base
and (expr / arg).is_number):
r = (self.expr.exp - arg.exp).is_positive
if not (r is None):
return not r
obj = self.func(expr, *self.args[1:])
return self.contains(obj)
def test_Limit():
assert str(Limit(sin(x)/x, x, y)) == "Limit(sin(x)/x, x, y)"
assert str(Limit(1/x, x, 0)) == "Limit(1/x, x, 0)"
assert str(
Limit(sin(x)/x, x, y, dir="-")) == "Limit(sin(x)/x, x, y, dir='-')"
(r"\lceil x \rceil", ceiling(x)),
(r"\langle x |", Bra('x')),
(r"| x \rangle", Ket('x')),
(r"\sin \theta", sin(theta)),
(r"\sin(\theta)", sin(theta)),
(r"\sin^{-1} a", asin(a)),
(r"\sin a \cos b", _Mul(sin(a), cos(b))),
(r"\sin \cos \theta", sin(cos(theta))),
(r"\sin(\cos \theta)", sin(cos(theta))),
(r"\frac{a}{b}", a / b),
(r"\dfrac{a}{b}", a / b),
(r"\tfrac{a}{b}", a / b),
(r"\frac{a + b}{c}", _Mul(a + b, _Pow(c, -1))),
(r"\frac{7}{3}", _Mul(7, _Pow(3, -1))),
(r"(\csc x)(\sec y)", csc(x) * sec(y)),
(r"\lim_{x \to 3} a", Limit(a, x, 3)),
(r"\lim_{x \rightarrow 3} a", Limit(a, x, 3)),
(r"\lim_{x \Rightarrow 3} a", Limit(a, x, 3)),
(r"\lim_{x \longrightarrow 3} a", Limit(a, x, 3)),
(r"\lim_{x \Longrightarrow 3} a", Limit(a, x, 3)),
(r"\lim_{x \to 3^{+}} a", Limit(a, x, 3, dir='+')),
(r"\lim_{x \to 3^{-}} a", Limit(a, x, 3, dir='-')),
(r"\infty", oo),
(r"\lim_{x \to \infty} \frac{1}{x}", Limit(_Pow(x, -1), x, oo)),
(r"\frac{d}{dx} x", Derivative(x, x)),
(r"\frac{d}{dt} x", Derivative(x, t)),
(r"f(x)", f(x)),
(r"f(x, y)", f(x, y)),
(r"f(x, y, z)", f(x, y, z)),
(r"\frac{d f(x)}{dx}", Derivative(f(x), x)),
(r"\frac{d\theta(x)}{dx}", Derivative(Function('theta')(x), x)),
def test_Limit():
assert Limit(sin(x)/x, x, 0) != 1
assert Limit(sin(x)/x, x, 0).doit() == 1
assert Limit(x, x, 0, dir='+-').args == (x, x, 0, Symbol('+-'))
def test_doit():
f = Integral(2 * x, x)
l = Limit(f, x, oo)
assert l.doit() is oo
def test_series():
e = Symbol("e")
x = Symbol("x")
for c in (Limit, Limit(e, x, 1), Order, Order(e)):
check(c)
def test_basic1():
assert limit(x, x, oo) is oo
assert limit(x, x, -oo) is -oo
assert limit(-x, x, oo) is -oo
assert limit(x**2, x, -oo) is oo
assert limit(-x**2, x, oo) is -oo
assert limit(x*log(x), x, 0, dir="+") == 0
assert limit(1/x, x, oo) == 0
assert limit(exp(x), x, oo) is oo
assert limit(-exp(x), x, oo) is -oo
assert limit(exp(x)/x, x, oo) is oo
assert limit(1/x - exp(-x), x, oo) == 0
assert limit(x + 1/x, x, oo) is oo
assert limit(x - x**2, x, oo) is -oo
assert limit((1 + x)**(1 + sqrt(2)), x, 0) == 1
assert limit((1 + x)**oo, x, 0) == Limit((x + 1)**oo, x, 0)
assert limit((1 + x)**oo, x, 0, dir='-') == Limit((x + 1)**oo, x, 0, dir='-')
assert limit((1 + x + y)**oo, x, 0, dir='-') == Limit((1 + x + y)**oo, x, 0, dir='-')
assert limit(y/x/log(x), x, 0) == -oo*sign(y)
assert limit(cos(x + y)/x, x, 0) == sign(cos(y))*oo
assert limit(gamma(1/x + 3), x, oo) == 2
assert limit(S.NaN, x, -oo) is S.NaN
assert limit(Order(2)*x, x, S.NaN) is S.NaN
assert limit(1/(x - 1), x, 1, dir="+") is oo
assert limit(1/(x - 1), x, 1, dir="-") is -oo
assert limit(1/(5 - x)**3, x, 5, dir="+") is -oo
assert limit(1/(5 - x)**3, x, 5, dir="-") is oo
assert limit(1/sin(x), x, pi, dir="+") is -oo
assert limit(1/sin(x), x, pi, dir="-") is oo
assert limit(1/cos(x), x, pi/2, dir="+") is -oo
assert limit(1/cos(x), x, pi/2, dir="-") is oo
assert limit(1/tan(x**3), x, (2*pi)**Rational(1, 3), dir="+") is oo
assert limit(1/tan(x**3), x, (2*pi)**Rational(1, 3), dir="-") is -oo
assert limit(1/cot(x)**3, x, (pi*Rational(3, 2)), dir="+") is -oo
assert limit(1/cot(x)**3, x, (pi*Rational(3, 2)), dir="-") is oo
assert limit(tan(x), x, oo) == AccumBounds(S.NegativeInfinity, S.Infinity)
assert limit(cot(x), x, oo) == AccumBounds(S.NegativeInfinity, S.Infinity)
assert limit(sec(x), x, oo) == AccumBounds(S.NegativeInfinity, S.Infinity)
assert limit(csc(x), x, oo) == AccumBounds(S.NegativeInfinity, S.Infinity)
# test bi-directional limits
assert limit(sin(x)/x, x, 0, dir="+-") == 1
assert limit(x**2, x, 0, dir="+-") == 0
assert limit(1/x**2, x, 0, dir="+-") is oo
# test failing bi-directional limits
assert limit(1/x, x, 0, dir="+-") is zoo
# approaching 0
# from dir="+"
assert limit(1 + 1/x, x, 0) is oo
# from dir='-'
# Add
assert limit(1 + 1/x, x, 0, dir='-') is -oo
# Pow
assert limit(x**(-2), x, 0, dir='-') is oo
assert limit(x**(-3), x, 0, dir='-') is -oo
assert limit(1/sqrt(x), x, 0, dir='-') == (-oo)*I
assert limit(x**2, x, 0, dir='-') == 0
assert limit(sqrt(x), x, 0, dir='-') == 0
assert limit(x**-pi, x, 0, dir='-') == oo/(-1)**pi
assert limit((1 + cos(x))**oo, x, 0) == Limit((cos(x) + 1)**oo, x, 0)
# test pull request 22491
assert limit(1/asin(x), x, 0, dir = '+') == oo
assert limit(1/asin(x), x, 0, dir = '-') == -oo
assert limit(1/sinh(x), x, 0, dir = '+') == oo
assert limit(1/sinh(x), x, 0, dir = '-') == -oo
assert limit(log(1/x) + 1/sin(x), x, 0, dir = '+') == oo
assert limit(log(1/x) + 1/x, x, 0, dir = '+') == oo
def contains(self, expr):
r"""
Return True if expr belongs to Order(self.expr, \*self.variables).
Return False if self belongs to expr.
Return None if the inclusion relation cannot be determined
(e.g. when self and expr have different symbols).
"""
from sympy import powsimp
if expr is S.Zero:
return True
if expr is S.NaN:
return False
point = self.point[0] if self.point else S.Zero
if expr.is_Order:
if (any(p != point for p in expr.point)
or any(p != point for p in self.point)):
return None
if expr.expr == self.expr:
# O(1) + O(1), O(1) + O(1, x), etc.
return all([x in self.args[1:] for x in expr.args[1:]])
if expr.expr.is_Add:
return all([self.contains(x) for x in expr.expr.args])
if self.expr.is_Add and point == S.Zero:
return any([
self.func(x, *self.args[1:]).contains(expr)
for x in self.expr.args
])
if self.variables and expr.variables:
common_symbols = tuple(
[s for s in self.variables if s in expr.variables])
elif self.variables:
common_symbols = self.variables
else:
common_symbols = expr.variables
if not common_symbols:
return None
if (self.expr.is_Power and len(self.variables) == 1
and self.variables == expr.variables):
symbol = self.variables[0]
other = expr.expr.as_independent(symbol, as_Add=False)[1]
if (other.is_Power and other.base == symbol
and self.expr.base == symbol):
if point == S.Zero:
rv = (self.expr.exp - other.exp).is_nonpositive
if point.is_infinite:
rv = (self.expr.exp - other.exp).is_nonnegative
if rv is not None:
return rv
r = None
ratio = self.expr / expr.expr
ratio = powsimp(ratio, deep=True, combine='exp')
for s in common_symbols:
from sympy.series.limits import Limit
l = Limit(ratio, s, point).doit(heuristics=False)
if not isinstance(l, Limit):
l = l != 0
else:
l = None
if r is None:
r = l
else:
if r != l:
return
return r
if self.expr.is_Power and len(self.variables) == 1:
symbol = self.variables[0]
other = expr.as_independent(symbol, as_Add=False)[1]
if (other.is_Power and other.base == symbol
and self.expr.base == symbol):
if point == S.Zero:
rv = (self.expr.exp - other.exp).is_nonpositive
if point.is_infinite:
rv = (self.expr.exp - other.exp).is_nonnegative
if rv is not None:
return rv
obj = self.func(expr, *self.args[1:])
return self.contains(obj)
def lens_formula(focal_length=None, u=None, v=None):
"""
This function provides one of the three parameters
when two of them are supplied.
This is valid only for paraxial rays.
Parameters
==========
focal_length : sympifiable
Focal length of the mirror.
u : sympifiable
Distance of object from the optical center on
the principal axis.
v : sympifiable
Distance of the image from the optical center
on the principal axis.
Examples
========
>>> from sympy.physics.optics import lens_formula
>>> from sympy.abc import f, u, v
>>> lens_formula(focal_length=f, u=u)
f*u/(f + u)
>>> lens_formula(focal_length=f, v=v)
f*v/(f - v)
>>> lens_formula(u=u, v=v)
u*v/(u - v)
"""
if focal_length and u and v:
raise ValueError("Please provide only two parameters")
focal_length = sympify(focal_length)
u = sympify(u)
v = sympify(v)
if u is oo:
_u = Symbol('u')
if v is oo:
_v = Symbol('v')
if focal_length is oo:
_f = Symbol('f')
if focal_length is None:
if u is oo and v is oo:
return Limit(Limit(_v * _u / (_u - _v), _u, oo), _v, oo).doit()
if u is oo:
return Limit(v * _u / (_u - v), _u, oo).doit()
if v is oo:
return Limit(_v * u / (u - _v), _v, oo).doit()
return v * u / (u - v)
if u is None:
if v is oo and focal_length is oo:
return Limit(Limit(_v * _f / (_f - _v), _v, oo), _f, oo).doit()
if v is oo:
return Limit(_v * focal_length / (focal_length - _v), _v,
oo).doit()
if focal_length is oo:
return Limit(v * _f / (_f - v), _f, oo).doit()
return v * focal_length / (focal_length - v)
if v is None:
if u is oo and focal_length is oo:
return Limit(Limit(_u * _f / (_u + _f), _u, oo), _f, oo).doit()
if u is oo:
return Limit(_u * focal_length / (_u + focal_length), _u,
oo).doit()
if focal_length is oo:
return Limit(u * _f / (u + _f), _f, oo).doit()
return u * focal_length / (u + focal_length)
