def test_solve_rational():
assert solveset_real(1/x + 1, x) == FiniteSet(-S.One)
assert solveset_real(1/exp(x) - 1, x) == FiniteSet(0)
assert solveset_real(x*(1 - 5/x), x) == FiniteSet(5)
assert solveset_real(2*x/(x + 2) - 1, x) == FiniteSet(2)
assert solveset_real((x**2/(7 - x)).diff(x), x) == \
FiniteSet(S(0), S(14))
def test_uselogcombine_1():
assert solveset_real(log(x - 3) + log(x + 3), x) == \
FiniteSet(sqrt(10))
assert solveset_real(log(x + 1) - log(2*x - 1), x) == FiniteSet(2)
assert solveset_real(log(x + 3) + log(1 + 3/x) - 3) == FiniteSet(
-3 + sqrt(-12 + exp(3))*exp(S(3)/2)/2 + exp(3)/2,
-sqrt(-12 + exp(3))*exp(S(3)/2)/2 - 3 + exp(3)/2)
def test_garbage_input():
raises(ValueError, lambda: solveset_real([x], x))
raises(ValueError, lambda: solveset_real(x, pi))
raises(ValueError, lambda: solveset_real(x, x ** 2))
raises(ValueError, lambda: solveset_complex([x], x))
raises(ValueError, lambda: solveset_complex(x, pi))
def test_solve_trig():
from sympy.abc import n
assert solveset_real(sin(x), x) == Union(
imageset(Lambda(n, 2 * pi * n), S.Integers), imageset(Lambda(n, 2 * pi * n + pi), S.Integers)
)
assert solveset_real(sin(x) - 1, x) == imageset(Lambda(n, 2 * pi * n + pi / 2), S.Integers)
assert solveset_real(cos(x), x) == Union(
imageset(Lambda(n, 2 * pi * n - pi / 2), S.Integers), imageset(Lambda(n, 2 * pi * n + pi / 2), S.Integers)
)
assert solveset_real(sin(x) + cos(x), x) == Union(
imageset(Lambda(n, 2 * n * pi - pi / 4), S.Integers), imageset(Lambda(n, 2 * n * pi + 3 * pi / 4), S.Integers)
)
assert solveset_real(sin(x) ** 2 + cos(x) ** 2, x) == S.EmptySet
assert solveset_complex(cos(x) - S.Half, x) == Union(
imageset(Lambda(n, 2 * n * pi + pi / 3), S.Integers), imageset(Lambda(n, 2 * n * pi - pi / 3), S.Integers)
)
y, a = symbols("y,a")
assert solveset(sin(y + a) - sin(y), a, domain=S.Reals) == Union(
imageset(Lambda(n, 2 * n * pi), S.Integers),
imageset(Lambda(n, -I * (I * (2 * n * pi + arg(-exp(-2 * I * y))) + 2 * im(y))), S.Integers),
)
def test_errorinverses():
assert solveset_real(erf(x) - S.One/2, x) == \
FiniteSet(erfinv(S.One/2))
assert solveset_real(erfinv(x) - 2, x) == \
FiniteSet(erf(2))
assert solveset_real(erfc(x) - S.One, x) == \
FiniteSet(erfcinv(S.One))
assert solveset_real(erfcinv(x) - 2, x) == FiniteSet(erfc(2))
def test_solve_abs():
assert solveset_real(Abs(x) - 2, x) == FiniteSet(-2, 2)
assert solveset_real(Abs(x + 3) - 2*Abs(x - 3), x) == \
FiniteSet(1, 9)
assert solveset_real(2*Abs(x) - Abs(x - 1), x) == \
FiniteSet(-1, Rational(1, 3))
assert solveset_real(Abs(x - 7) - 8, x) == FiniteSet(-S(1), S(15))
def test_piecewise():
eq = Piecewise((x - 2, Gt(x, 2)), (2 - x, True)) - 3
f = Piecewise(((x - 2) ** 2, x >= 0), (0, True))
assert set(solveset_real(eq, x)) == set(FiniteSet(-1, 5))
absxm3 = Piecewise((x - 3, S(0) <= x - 3), (3 - x, S(0) > x - 3))
y = Symbol("y", positive=True)
assert solveset_real(absxm3 - y, x) == FiniteSet(-y + 3, y + 3)
assert solveset(f, x, domain=S.Reals) == Union(FiniteSet(2), Interval(-oo, 0, True, True))
def test_solve_trig_simplified():
from sympy.abc import n
assert solveset_real(sin(x), x) == imageset(Lambda(n, n * pi), S.Integers)
assert solveset_real(cos(x), x) == imageset(Lambda(n, n * pi + pi / 2), S.Integers)
assert solveset_real(cos(x) + sin(x), x) == imageset(Lambda(n, n * pi - pi / 4), S.Integers)
def test_piecewise():
eq = Piecewise((x - 2, Gt(x, 2)), (2 - x, True)) - 3
assert set(solveset_real(eq, x)) == set(FiniteSet(-1, 5))
absxm3 = Piecewise(
(x - 3, S(0) <= x - 3),
(3 - x, S(0) > x - 3)
)
y = Symbol('y', positive=True)
assert solveset_real(absxm3 - y, x) == FiniteSet(-y + 3, y + 3)
def test_solve_polynomial_cv_1a():
"""
Test for solving on equations that can be converted to
a polynomial equation using the change of variable y -> x**Rational(p, q)
"""
assert solveset_real(sqrt(x) - 1, x) == FiniteSet(1)
assert solveset_real(sqrt(x) - 2, x) == FiniteSet(4)
assert solveset_real(x ** Rational(1, 4) - 2, x) == FiniteSet(16)
assert solveset_real(x ** Rational(1, 3) - 3, x) == FiniteSet(27)
assert solveset_real(x * (x ** (S(1) / 3) - 3), x) == FiniteSet(S(0), S(27))
def test_piecewise():
eq = Piecewise((x - 2, Gt(x, 2)), (2 - x, True)) - 3
assert set(solveset_real(eq, x)) == set(FiniteSet(-1, 5))
absxm3 = Piecewise(
(x - 3, S(0) <= x - 3),
(3 - x, S(0) > x - 3))
y = Symbol('y', positive=True)
assert solveset_real(absxm3 - y, x) == FiniteSet(-y + 3, y + 3)
f = Piecewise(((x - 2)**2, x >= 0), (0, True))
assert solveset(f, x, domain=S.Reals) == Union(FiniteSet(2), Interval(-oo, 0, True, True))
assert solveset(Piecewise((x + 1, x > 0), (I, True)) - I, x) == \
Interval(-oo, 0)
def test_solve_polynomial():
assert solveset_real(3 * x - 2, x) == FiniteSet(Rational(2, 3))
assert solveset_real(x ** 2 - 1, x) == FiniteSet(-S(1), S(1))
assert solveset_real(x - y ** 3, x) == FiniteSet(y ** 3)
a11, a12, a21, a22, b1, b2 = symbols("a11, a12, a21, a22, b1, b2")
assert solveset_real(x ** 3 - 15 * x - 4, x) == FiniteSet(-2 + 3 ** Rational(1, 2), S(4), -2 - 3 ** Rational(1, 2))
assert solveset_real(sqrt(x) - 1, x) == FiniteSet(1)
assert solveset_real(sqrt(x) - 2, x) == FiniteSet(4)
assert solveset_real(x ** Rational(1, 4) - 2, x) == FiniteSet(16)
assert solveset_real(x ** Rational(1, 3) - 3, x) == FiniteSet(27)
assert len(solveset_real(x ** 5 + x ** 3 + 1, x)) == 1
assert len(solveset_real(-2 * x ** 3 + 4 * x ** 2 - 2 * x + 6, x)) > 0
def test_solve_sqrt_3():
R = Symbol("R")
eq = sqrt(2) * R * sqrt(1 / (R + 1)) + (R + 1) * (sqrt(2) * sqrt(1 / (R + 1)) - 1)
sol = solveset_complex(eq, R)
assert sol == FiniteSet(
*[
S(5) / 3 + 4 * sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) / 3,
-sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) / 3
+ 40 * re(1 / ((-S(1) / 2 - sqrt(3) * I / 2) * (S(251) / 27 + sqrt(111) * I / 9) ** (S(1) / 3))) / 9
+ sqrt(30) * sin(atan(3 * sqrt(111) / 251) / 3) / 3
+ S(5) / 3
+ I
* (
-sqrt(30) * cos(atan(3 * sqrt(111) / 251) / 3) / 3
- sqrt(10) * sin(atan(3 * sqrt(111) / 251) / 3) / 3
+ 40 * im(1 / ((-S(1) / 2 - sqrt(3) * I / 2) * (S(251) / 27 + sqrt(111) * I / 9) ** (S(1) / 3))) / 9
),
]
)
# the number of real roots will depend on the value of m: for m=1 there are 4
# and for m=-1 there are none.
eq = -sqrt((m - q) ** 2 + (-m / (2 * q) + S(1) / 2) ** 2) + sqrt(
(-m ** 2 / 2 - sqrt(4 * m ** 4 - 4 * m ** 2 + 8 * m + 1) / 4 - S(1) / 4) ** 2
+ (m ** 2 / 2 - m - sqrt(4 * m ** 4 - 4 * m ** 2 + 8 * m + 1) / 4 - S(1) / 4) ** 2
)
raises(NotImplementedError, lambda: solveset_real(eq, q))
def test_solve_sqrt_3():
R = Symbol('R')
eq = sqrt(2) * R * sqrt(1 /
(R + 1)) + (R + 1) * (sqrt(2) * sqrt(1 /
(R + 1)) - 1)
sol = solveset_complex(eq, R)
assert sol == FiniteSet(*[
S(5) / 3 + 4 * sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) /
3, -sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) / 3 +
40 * re(1 / ((-S(1) / 2 - sqrt(3) * I / 2) *
(S(251) / 27 + sqrt(111) * I / 9)**(S(1) / 3))) / 9 +
sqrt(30) * sin(atan(3 * sqrt(111) / 251) / 3) / 3 + S(5) / 3 + I *
(-sqrt(30) * cos(atan(3 * sqrt(111) / 251) / 3) / 3 -
sqrt(10) * sin(atan(3 * sqrt(111) / 251) / 3) / 3 + 40 * im(1 / (
(-S(1) / 2 - sqrt(3) * I / 2) *
(S(251) / 27 + sqrt(111) * I / 9)**(S(1) / 3))) / 9)
])
# the number of real roots will depend on the value of m: for m=1 there are 4
# and for m=-1 there are none.
eq = -sqrt((m - q)**2 + (-m / (2 * q) + S(1) / 2)**2) + sqrt(
(-m**2 / 2 - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 - S(1) / 4)**2 +
(m**2 / 2 - m - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 -
S(1) / 4)**2)
raises(NotImplementedError, lambda: solveset_real(eq, q))
def test_solve_sqrt_3():
R = Symbol('R')
eq = sqrt(2) * R * sqrt(1 /
(R + 1)) + (R + 1) * (sqrt(2) * sqrt(1 /
(R + 1)) - 1)
sol = solveset_complex(eq, R)
assert sol == FiniteSet(*[
S(5) / 3 + 4 * sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) /
3, -sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) / 3 +
40 * re(1 / ((-S(1) / 2 - sqrt(3) * I / 2) *
(S(251) / 27 + sqrt(111) * I / 9)**(S(1) / 3))) / 9 +
sqrt(30) * sin(atan(3 * sqrt(111) / 251) / 3) / 3 + S(5) / 3 + I *
(-sqrt(30) * cos(atan(3 * sqrt(111) / 251) / 3) / 3 -
sqrt(10) * sin(atan(3 * sqrt(111) / 251) / 3) / 3 + 40 * im(1 / (
(-S(1) / 2 - sqrt(3) * I / 2) *
(S(251) / 27 + sqrt(111) * I / 9)**(S(1) / 3))) / 9)
])
# the number of real roots will depend on the value of m: for m=1 there are 4
# and for m=-1 there are none.
eq = -sqrt((m - q)**2 + (-m / (2 * q) + S(1) / 2)**2) + sqrt(
(-m**2 / 2 - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 - S(1) / 4)**2 +
(m**2 / 2 - m - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 -
S(1) / 4)**2)
unsolved_object = ConditionSet(
q,
Eq((-2 * sqrt(4 * q**2 * (m - q)**2 + (-m + q)**2) + sqrt(
(-2 * m**2 - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) - 1)**2 +
(2 * m**2 - 4 * m - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) - 1)**2)
* Abs(q)) / Abs(q), 0), S.Reals)
assert solveset_real(eq, q) == unsolved_object
def test_rewrite_trigh():
# if this import passes then the test below should also pass
from sympy import sech
assert solveset_real(sinh(x) + sech(x), x) == FiniteSet(
2 * atanh(-S.Half + sqrt(5) / 2 - sqrt(-2 * sqrt(5) + 2) / 2),
2 * atanh(-S.Half + sqrt(5) / 2 + sqrt(-2 * sqrt(5) + 2) / 2),
2 * atanh(-sqrt(5) / 2 - S.Half + sqrt(2 + 2 * sqrt(5)) / 2),
2 * atanh(-sqrt(2 + 2 * sqrt(5)) / 2 - sqrt(5) / 2 - S.Half))
def test_rewrite_trigh():
# if this import passes then the test below should also pass
from sympy import sech
assert solveset_real(sinh(x) + sech(x), x) == FiniteSet(
2*atanh(-S.Half + sqrt(5)/2 - sqrt(-2*sqrt(5) + 2)/2),
2*atanh(-S.Half + sqrt(5)/2 + sqrt(-2*sqrt(5) + 2)/2),
2*atanh(-sqrt(5)/2 - S.Half + sqrt(2 + 2*sqrt(5))/2),
2*atanh(-sqrt(2 + 2*sqrt(5))/2 - sqrt(5)/2 - S.Half))
def codomain_interval(f, set_val, *sym):
symb = sym[0]
df1 = diff(f, symb)
df2 = diff(df1, symb)
der_zero = solveset_real(df1, symb)
der_zero_in_dom = closure_handle(set_val, der_zero)
local_maxima = set()
local_minima = set()
start_val = limit(f, symb, set_val.start)
end_val = limit(f, symb, set_val.end, '-')
if start_val is S.Infinity or end_val is S.Infinity:
local_maxima = set([(oo, True)])
elif start_val is S.NegativeInfinity or end_val is S.NegativeInfinity:
local_minima = set([(-oo, True)])
if local_maxima == set():
if start_val > end_val:
local_maxima = set([(start_val, set_val.left_open)])
elif start_val < end_val:
local_maxima = set([(end_val, set_val.right_open)])
else:
local_maxima = set([(start_val, set_val.left_open
and set_val.right_open)])
if local_minima == set():
if start_val < end_val:
local_minima = set([(start_val, set_val.left_open)])
elif start_val > end_val:
local_minima = set([(end_val, set_val.right_open)])
else:
local_minima = set([(start_val, set_val.left_open
and set_val.right_open)])
for i in der_zero_in_dom:
exist = not i in set_val
if df2.subs({symb: i}) < 0:
local_maxima.add((f.subs({symb: i}), exist))
elif df2.subs({symb: i}) > 0:
local_minima.add((f.subs({symb: i}), exist))
maximum = (-oo, True)
minimum = (oo, True)
for i in local_maxima:
if i[0] > maximum[0]:
maximum = i
elif i[0] == maximum[0]:
maximum = (maximum[0], i[1] and maximum[1])
for i in local_minima:
if i[0] < minimum[0]:
minimum = i
elif i[0] == minimum[0]:
minimum = (minimum[0], i[1] and minimum[1])
return Union(Interval(minimum[0], maximum[0], minimum[1], maximum[1]))
def test_solve_trig():
from sympy.abc import n
assert solveset_real(sin(x), x) == \
Union(imageset(Lambda(n, 2*pi*n), S.Integers),
imageset(Lambda(n, 2*pi*n + pi), S.Integers))
assert solveset_real(sin(x) - 1, x) == \
imageset(Lambda(n, 2*pi*n + pi/2), S.Integers)
assert solveset_real(cos(x), x) == \
Union(imageset(Lambda(n, 2*pi*n - pi/2), S.Integers),
imageset(Lambda(n, 2*pi*n + pi/2), S.Integers))
assert solveset_real(sin(x) + cos(x), x) == \
Union(imageset(Lambda(n, 2*n*pi - pi/4), S.Integers),
imageset(Lambda(n, 2*n*pi + 3*pi/4), S.Integers))
assert solveset_real(sin(x)**2 + cos(x)**2, x) == S.EmptySet
def test_solve_abs():
assert solveset_real(Abs(x) - 2, x) == FiniteSet(-2, 2)
assert solveset_real(Abs(x + 3) - 2 * Abs(x - 3), x) == FiniteSet(1, 9)
assert solveset_real(2 * Abs(x) - Abs(x - 1), x) == FiniteSet(-1, Rational(1, 3))
assert solveset_real(Abs(x - 7) - 8, x) == FiniteSet(-S(1), S(15))
# issue 9565. Note: solveset_real does not solve this as it is
# solveset's job to handle Relationals
assert solveset(Abs((x - 1) / (x - 5)) <= S(1) / 3, domain=S.Reals) == Interval(-1, 2)
# issue #10069
eq = abs(1 / (x - 1)) - 1 > 0
u = Union(Interval.open(0, 1), Interval.open(1, 2))
assert solveset_real(eq, x) == u
assert solveset(eq, x, domain=S.Reals) == u
raises(ValueError, lambda: solveset(abs(x) - 1, x))
def test_solve_polynomial():
assert solveset_real(3 * x - 2, x) == FiniteSet(Rational(2, 3))
assert solveset_real(x**2 - 1, x) == FiniteSet(-S(1), S(1))
assert solveset_real(x - y**3, x) == FiniteSet(y**3)
a11, a12, a21, a22, b1, b2 = symbols('a11, a12, a21, a22, b1, b2')
assert solveset_real(x**3 - 15 * x - 4,
x) == FiniteSet(-2 + 3**Rational(1, 2), S(4),
-2 - 3**Rational(1, 2))
assert solveset_real(sqrt(x) - 1, x) == FiniteSet(1)
assert solveset_real(sqrt(x) - 2, x) == FiniteSet(4)
assert solveset_real(x**Rational(1, 4) - 2, x) == FiniteSet(16)
assert solveset_real(x**Rational(1, 3) - 3, x) == FiniteSet(27)
assert len(solveset_real(x**5 + x**3 + 1, x)) == 1
assert len(solveset_real(-2 * x**3 + 4 * x**2 - 2 * x + 6, x)) > 0
def test_solve_trig():
from sympy.abc import n
assert solveset_real(sin(x), x) == \
Union(imageset(Lambda(n, 2*pi*n), S.Integers),
imageset(Lambda(n, 2*pi*n + pi), S.Integers))
assert solveset_real(sin(x) - 1, x) == \
imageset(Lambda(n, 2*pi*n + pi/2), S.Integers)
assert solveset_real(cos(x), x) == \
Union(imageset(Lambda(n, 2*pi*n - pi/2), S.Integers),
imageset(Lambda(n, 2*pi*n + pi/2), S.Integers))
assert solveset_real(sin(x) + cos(x), x) == \
Union(imageset(Lambda(n, 2*n*pi - pi/4), S.Integers),
imageset(Lambda(n, 2*n*pi + 3*pi/4), S.Integers))
assert solveset_real(sin(x)**2 + cos(x)**2, x) == S.EmptySet
def codomain_interval(f, set_val, *sym):
symb = sym[0]
df1 = diff(f, symb)
df2 = diff(df1, symb)
der_zero = solveset_real(df1, symb)
der_zero_in_dom = closure_handle(set_val, der_zero)
local_maxima = set()
local_minima = set()
start_val = limit(f, symb, set_val.start)
end_val = limit(f, symb, set_val.end, '-')
if start_val is S.Infinity or end_val is S.Infinity:
local_maxima = set([(oo, True)])
elif start_val is S.NegativeInfinity or end_val is S.NegativeInfinity:
local_minima = set([(-oo, True)])
if local_maxima == set():
if start_val > end_val:
local_maxima = set([(start_val, set_val.left_open)])
elif start_val < end_val:
local_maxima = set([(end_val, set_val.right_open)])
else:
local_maxima = set([(start_val, set_val.left_open and set_val.right_open)])
if local_minima == set():
if start_val < end_val:
local_minima = set([(start_val, set_val.left_open)])
elif start_val > end_val:
local_minima = set([(end_val, set_val.right_open)])
else:
local_minima = set([(start_val, set_val.left_open and set_val.right_open)])
for i in der_zero_in_dom:
exist = not i in set_val
if df2.subs({symb: i}) < 0:
local_maxima.add((f.subs({symb: i}), exist))
elif df2.subs({symb: i}) > 0:
local_minima.add((f.subs({symb: i}), exist))
maximum = (-oo, True)
minimum = (oo, True)
for i in local_maxima:
if i[0] > maximum[0]:
maximum = i
elif i[0] == maximum[0]:
maximum = (maximum[0], i[1] and maximum[1])
for i in local_minima:
if i[0] < minimum[0]:
minimum = i
elif i[0] == minimum[0]:
minimum = (minimum[0], i[1] and minimum[1])
return Union(Interval(minimum[0], maximum[0], minimum[1], maximum[1]))
def test_solve_abs():
assert solveset_real(Abs(x) - 2, x) == FiniteSet(-2, 2)
assert solveset_real(Abs(x + 3) - 2*Abs(x - 3), x) == \
FiniteSet(1, 9)
assert solveset_real(2*Abs(x) - Abs(x - 1), x) == \
FiniteSet(-1, Rational(1, 3))
assert solveset_real(Abs(x - 7) - 8, x) == FiniteSet(-S(1), S(15))
# issue 9565. Note: solveset_real does not solve this as it is
# solveset's job to handle Relationals
assert solveset(Abs((x - 1)/(x - 5)) <= S(1)/3, domain=S.Reals
) == Interval(-1, 2)
# issue #10069
assert solveset_real(abs(1/(x - 1)) - 1 > 0, x) == \
ConditionSet(x, Eq((1 - Abs(x - 1))/Abs(x - 1) > 0, 0),
S.Reals)
assert solveset(abs(1/(x - 1)) - 1 > 0, x, domain=S.Reals
) == Union(Interval.open(0, 1), Interval.open(1, 2))
def test_solve_abs():
assert solveset_real(Abs(x) - 2, x) == FiniteSet(-2, 2)
assert solveset_real(Abs(x + 3) - 2*Abs(x - 3), x) == \
FiniteSet(1, 9)
assert solveset_real(2*Abs(x) - Abs(x - 1), x) == \
FiniteSet(-1, Rational(1, 3))
assert solveset_real(Abs(x - 7) - 8, x) == FiniteSet(-S(1), S(15))
# issue 9565. Note: solveset_real does not solve this as it is
# solveset's job to handle Relationals
assert solveset(Abs((x - 1)/(x - 5)) <= S(1)/3, domain=S.Reals
) == Interval(-1, 2)
# issue #10069
assert solveset_real(abs(1/(x - 1)) - 1 > 0, x) == \
ConditionSet(x, Eq((1 - Abs(x - 1))/Abs(x - 1) > 0, 0),
S.Reals)
assert solveset(abs(1/(x - 1)) - 1 > 0, x, domain=S.Reals
) == Union(Interval.open(0, 1), Interval.open(1, 2))
def getTmOptimal2(v0, vt, p0, pt, delay=0.0):
t = symbols('t')
a = (12.0 * (t * (p0 - pt + t*v0) - 0.5*(t**2)*(v0 - vt)))/(t**4)
b = -(4 * (1.5*(p0 - pt) + t*v0 + 0.5*t*vt))/(t**2)
j = ((a*t + b)**3 - b**3) / a
djdt = diff(j, t)
try:
res = solveset_real(djdt, t)
except Exception as e:
res = solve(djdt, t)
print("Calculating tm for v0={}, vt={}, p0={}, pt={}, tm={}".format(v0, vt, p0, pt, float(min(res))))
return float(min(res)) + delay
def test_solve_abs():
assert solveset_real(Abs(x) - 2, x) == FiniteSet(-2, 2)
assert solveset_real(Abs(x + 3) - 2*Abs(x - 3), x) == \
FiniteSet(1, 9)
assert solveset_real(2*Abs(x) - Abs(x - 1), x) == \
FiniteSet(-1, Rational(1, 3))
assert solveset_real(Abs(x - 7) - 8, x) == FiniteSet(-S(1), S(15))
# issue 9565. Note: solveset_real does not solve this as it is
# solveset's job to handle Relationals
assert solveset(Abs((x - 1) / (x - 5)) <= S(1) / 3,
domain=S.Reals) == Interval(-1, 2)
# issue #10069
eq = abs(1 / (x - 1)) - 1 > 0
u = Union(Interval.open(0, 1), Interval.open(1, 2))
assert solveset_real(eq, x) == u
assert solveset(eq, x, domain=S.Reals) == u
raises(ValueError, lambda: solveset(abs(x) - 1, x))
def test_no_sol():
assert solveset_real(4, x) == EmptySet()
assert solveset_real(exp(x), x) == EmptySet()
assert solveset_real(x ** 2 + 1, x) == EmptySet()
assert solveset_real(-3 * a / sqrt(x), x) == EmptySet()
assert solveset_real(1 / x, x) == EmptySet()
assert solveset_real(-(1 + x) / (2 + x) ** 2 + 1 / (2 + x), x) == EmptySet()
def test_solveset_sqrt_1():
assert solveset_real(sqrt(5 * x + 6) - 2 - x, x) == FiniteSet(-S(1), S(2))
assert solveset_real(sqrt(x - 1) - x + 7, x) == FiniteSet(10)
assert solveset_real(sqrt(x - 2) - 5, x) == FiniteSet(27)
assert solveset_real(sqrt(x) - 2 - 5, x) == FiniteSet(49)
assert solveset_real(sqrt(x ** 3), x) == FiniteSet(0)
assert solveset_real(sqrt(x - 1), x) == FiniteSet(1)
def test_no_sol():
assert solveset_real(4, x) == EmptySet()
assert solveset_real(exp(x), x) == EmptySet()
assert solveset_real(x**2 + 1, x) == EmptySet()
assert solveset_real(-3 * a / sqrt(x), x) == EmptySet()
assert solveset_real(1 / x, x) == EmptySet()
assert solveset_real(-(1 + x)/(2 + x)**2 + 1/(2 + x), x) == \
EmptySet()
def test_solveset_sqrt_1():
assert solveset_real(sqrt(5*x + 6) - 2 - x, x) == \
FiniteSet(-S(1), S(2))
assert solveset_real(sqrt(x - 1) - x + 7, x) == FiniteSet(10)
assert solveset_real(sqrt(x - 2) - 5, x) == FiniteSet(27)
assert solveset_real(sqrt(x) - 2 - 5, x) == FiniteSet(49)
assert solveset_real(sqrt(x**3), x) == FiniteSet(0)
assert solveset_real(sqrt(x - 1), x) == FiniteSet(1)
def _intersect(self, other):
from sympy.solvers.diophantine import diophantine
if self.base_set is S.Integers:
g = None
if isinstance(other, ImageSet) and other.base_set is S.Integers:
g = other.lamda.expr
m = other.lamda.variables[0]
elif other is S.Integers:
m = g = Dummy('x')
if g is not None:
f = self.lamda.expr
n = self.lamda.variables[0]
# Diophantine sorts the solutions according to the alphabetic
# order of the variable names, since the result should not depend
# on the variable name, they are replaced by the dummy variables
# below
a, b = Dummy('a'), Dummy('b')
f, g = f.subs(n, a), g.subs(m, b)
solns_set = diophantine(f - g)
if solns_set == set():
return EmptySet()
solns = list(diophantine(f - g))
if len(solns) != 1:
return
# since 'a' < 'b', select soln for n
nsol = solns[0][0]
t = nsol.free_symbols.pop()
return imageset(Lambda(n, f.subs(a, nsol.subs(t, n))), S.Integers)
if other == S.Reals:
from sympy.solvers.solveset import solveset_real
from sympy.core.function import expand_complex
if len(self.lamda.variables) > 1:
return None
f = self.lamda.expr
n = self.lamda.variables[0]
n_ = Dummy(n.name, real=True)
f_ = f.subs(n, n_)
re, im = f_.as_real_imag()
im = expand_complex(im)
return imageset(Lambda(n_, re),
self.base_set.intersect(
solveset_real(im, n_)))
def _intersect(self, other):
from sympy.solvers.diophantine import diophantine
if self.base_set is S.Integers:
g = None
if isinstance(other, ImageSet) and other.base_set is S.Integers:
g = other.lamda.expr
m = other.lamda.variables[0]
elif other is S.Integers:
m = g = Dummy('x')
if g is not None:
f = self.lamda.expr
n = self.lamda.variables[0]
# Diophantine sorts the solutions according to the alphabetic
# order of the variable names, since the result should not depend
# on the variable name, they are replaced by the dummy variables
# below
a, b = Dummy('a'), Dummy('b')
f, g = f.subs(n, a), g.subs(m, b)
solns_set = diophantine(f - g)
if solns_set == set():
return EmptySet()
solns = list(diophantine(f - g))
if len(solns) != 1:
return
# since 'a' < 'b', select soln for n
nsol = solns[0][0]
t = nsol.free_symbols.pop()
return imageset(Lambda(n, f.subs(a, nsol.subs(t, n))),
S.Integers)
if other == S.Reals:
from sympy.solvers.solveset import solveset_real
from sympy.core.function import expand_complex
if len(self.lamda.variables) > 1:
return None
f = self.lamda.expr
n = self.lamda.variables[0]
n_ = Dummy(n.name, real=True)
f_ = f.subs(n, n_)
re, im = f_.as_real_imag()
im = expand_complex(im)
return imageset(Lambda(n_, re),
self.base_set.intersect(solveset_real(im, n_)))
def test_solve_invert():
assert solveset_real(exp(x) - 3, x) == FiniteSet(log(3))
assert solveset_real(log(x) - 3, x) == FiniteSet(exp(3))
assert solveset_real(3**(x + 2), x) == FiniteSet()
assert solveset_real(3**(2 - x), x) == FiniteSet()
assert solveset_real(y - b*exp(a/x), x) == Intersection(S.Reals, FiniteSet(a/log(y/b)))
# issue 4504
assert solveset_real(2**x - 10, x) == FiniteSet(log(10)/log(2))
def test_solve_invert():
assert solveset_real(exp(x) - 3, x) == FiniteSet(log(3))
assert solveset_real(log(x) - 3, x) == FiniteSet(exp(3))
assert solveset_real(3 ** (x + 2), x) == FiniteSet()
assert solveset_real(3 ** (2 - x), x) == FiniteSet()
assert solveset_real(y - b * exp(a / x), x) == Intersection(S.Reals, FiniteSet(a / log(y / b)))
# issue 4504
assert solveset_real(2 ** x - 10, x) == FiniteSet(log(10) / log(2))
def test_solve_invert():
assert solveset_real(exp(x) - 3, x) == FiniteSet(log(3))
assert solveset_real(log(x) - 3, x) == FiniteSet(exp(3))
assert solveset_real(3**(x + 2), x) == FiniteSet()
assert solveset_real(3**(2 - x), x) == FiniteSet()
b = Symbol('b', positive=True)
y = Symbol('y', positive=True)
assert solveset_real(y - b*exp(a/x), x) == FiniteSet(a/log(y/b))
# issue 4504
assert solveset_real(2**x - 10, x) == FiniteSet(log(10)/log(2))
def test_solve_invert():
assert solveset_real(exp(x) - 3, x) == FiniteSet(log(3))
assert solveset_real(log(x) - 3, x) == FiniteSet(exp(3))
assert solveset_real(3**(x + 2), x) == FiniteSet()
assert solveset_real(3**(2 - x), x) == FiniteSet()
b = Symbol('b', positive=True)
y = Symbol('y', positive=True)
assert solveset_real(y - b * exp(a / x), x) == FiniteSet(a / log(y / b))
# issue 4504
assert solveset_real(2**x - 10, x) == FiniteSet(log(10) / log(2))
def _intersect(self, other):
from sympy import Dummy
from sympy.solvers.diophantine import diophantine
from sympy.sets.sets import imageset
if self.base_set is S.Integers:
if isinstance(other, ImageSet) and other.base_set is S.Integers:
f, g = self.lamda.expr, other.lamda.expr
n, m = self.lamda.variables[0], other.lamda.variables[0]
# Diophantine sorts the solutions according to the alphabetic
# order of the variable names, since the result should not depend
# on the variable name, they are replaced by the dummy variables
# below
a, b = Dummy("a"), Dummy("b")
f, g = f.subs(n, a), g.subs(m, b)
solns_set = diophantine(f - g)
if solns_set == set():
return EmptySet()
solns = list(diophantine(f - g))
if len(solns) == 1:
t = list(solns[0][0].free_symbols)[0]
else:
return None
# since 'a' < 'b'
return imageset(Lambda(t, f.subs(a, solns[0][0])), S.Integers)
if other == S.Reals:
from sympy.solvers.solveset import solveset_real
from sympy.core.function import expand_complex
if len(self.lamda.variables) > 1:
return None
f = self.lamda.expr
n = self.lamda.variables[0]
n_ = Dummy(n.name, real=True)
f_ = f.subs(n, n_)
re, im = f_.as_real_imag()
im = expand_complex(im)
return imageset(Lambda(n_, re), self.base_set.intersect(solveset_real(im, n_)))
def test_solve_sqrt_3():
R = Symbol("R")
eq = sqrt(2) * R * sqrt(1 / (R + 1)) + (R + 1) * (sqrt(2) * sqrt(1 / (R + 1)) - 1)
sol = solveset_complex(eq, R)
assert sol == FiniteSet(
*[
S(5) / 3 + 4 * sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) / 3,
-sqrt(10) * cos(atan(3 * sqrt(111) / 251) / 3) / 3
+ 40 * re(1 / ((-S(1) / 2 - sqrt(3) * I / 2) * (S(251) / 27 + sqrt(111) * I / 9) ** (S(1) / 3))) / 9
+ sqrt(30) * sin(atan(3 * sqrt(111) / 251) / 3) / 3
+ S(5) / 3
+ I
* (
-sqrt(30) * cos(atan(3 * sqrt(111) / 251) / 3) / 3
- sqrt(10) * sin(atan(3 * sqrt(111) / 251) / 3) / 3
+ 40 * im(1 / ((-S(1) / 2 - sqrt(3) * I / 2) * (S(251) / 27 + sqrt(111) * I / 9) ** (S(1) / 3))) / 9
),
]
)
# the number of real roots will depend on the value of m: for m=1 there are 4
# and for m=-1 there are none.
eq = -sqrt((m - q) ** 2 + (-m / (2 * q) + S(1) / 2) ** 2) + sqrt(
(-m ** 2 / 2 - sqrt(4 * m ** 4 - 4 * m ** 2 + 8 * m + 1) / 4 - S(1) / 4) ** 2
+ (m ** 2 / 2 - m - sqrt(4 * m ** 4 - 4 * m ** 2 + 8 * m + 1) / 4 - S(1) / 4) ** 2
)
unsolved_object = ConditionSet(
q,
Eq(
(
-2 * sqrt(4 * q ** 2 * (m - q) ** 2 + (-m + q) ** 2)
+ sqrt(
(-2 * m ** 2 - sqrt(4 * m ** 4 - 4 * m ** 2 + 8 * m + 1) - 1) ** 2
+ (2 * m ** 2 - 4 * m - sqrt(4 * m ** 4 - 4 * m ** 2 + 8 * m + 1) - 1) ** 2
)
* Abs(q)
)
/ Abs(q),
0,
),
S.Reals,
)
assert solveset_real(eq, q) == unsolved_object
def test_solve_sqrt_3():
R = Symbol('R')
eq = sqrt(2)*R*sqrt(1/(R + 1)) + (R + 1)*(sqrt(2)*sqrt(1/(R + 1)) - 1)
sol = solveset_complex(eq, R)
assert sol == FiniteSet(*[(S(5)/3 + 40/(3*(251 + 3*sqrt(111)*I)**(S(1)/3)) +
(251 + 3*sqrt(111)*I)**(S(1)/3)/3,), ((-160 + (1 +
sqrt(3)*I)*(10 - (1 + sqrt(3)*I)*(251 +
3*sqrt(111)*I)**(S(1)/3))*(251 +
3*sqrt(111)*I)**(S(1)/3))/Mul(6, (1 +
sqrt(3)*I), (251 + 3*sqrt(111)*I)**(S(1)/3),
evaluate=False),)])
eq = -sqrt((m - q)**2 + (-m/(2*q) + S(1)/2)**2) + sqrt((-m**2/2 - sqrt(
4*m**4 - 4*m**2 + 8*m + 1)/4 - S(1)/4)**2 + (m**2/2 - m - sqrt(
4*m**4 - 4*m**2 + 8*m + 1)/4 - S(1)/4)**2)
assert solveset_real(eq, q) == FiniteSet(
m**2/2 - sqrt(4*m**4 - 4*m**2 + 8*m + 1)/4 - S(1)/4,
m**2/2 + sqrt(4*m**4 - 4*m**2 + 8*m + 1)/4 - S(1)/4)
def solve_beguenstigungsbetrag(gewinn, hebesatz):
"""
Berechnung des Thesaurierungshöchstbetrags
:param gewinn: gewinn = zu versteuerndes Einkommen
:param hebesatz: Hebesatz der Gemeinden gem. § 16 GewStG (in Prozent: Bsp. 480)
:return: Thesaurierungshöchstbetrag
"""
eq1 = Eq(
B,
gewinn - calc_gewst(gewinn, hebesatz, 1) - calc_est(gewinn - B) +
calc_anrechnung_gewst(gewinn, hebesatz) - calc_est34a(B) - calc_solz(
calc_est(gewinn - B) # BMG für SolZ
- calc_anrechnung_gewst(gewinn, hebesatz) # BMG für SolZ
+ calc_est34a(B), # BMG für SolZ
einkommensteuerpflichtig=1))
sol = solveset_real(
eq1, B).args[0] # Das erste Argument der Lösung wird ausgegeben
return sol
def trust_region_step(g, B, delta):
# Calculates the trust region
lamb = sp.Symbol('lamb')
eigh = np.linalg.eig(B)
# B is positive definite
if eigh[0][0] > 0 and eigh[0][1] > 0:
pMin = -np.linalg.solve(B, g)
pMin_norm = np.linalg.norm(pMin, 2)
if pMin_norm <= delta:
return pMin
# B is not positive definite
q1T = np.transpose(eigh[1][:, 0])
q2T = np.transpose(eigh[1][:, 1])
# Setting up the equation
pLambda = ((np.dot(q1T, g) ** 2) / ((eigh[0][0] + lamb) ** 2)) \
+ ((np.dot(q2T, g) ** 2) / ((eigh[0][1] + lamb) ** 2)) \
- delta ** 2
# Symbolically solving
lamb_solved = solveset_real(pLambda[0], lamb)
lamb_solved = list(lamb_solved)
# Getting the lambda
for i in range(len(lamb_solved)):
# Lambda needs to be strictly positive and greater than negative of smallest eig
if lamb_solved[i] > 0 and lamb_solved[i] > -min(eigh[0]):
lamb_pos = lamb_solved[i]
BlambI = B + lamb_pos * np.identity(2)
BlambI = BlambI.astype(np.float)
pMin = np.linalg.solve(BlambI, -g)
return pMin
def test_solve_sqrt_3():
R = Symbol('R')
eq = sqrt(2) * R * sqrt(1 /
(R + 1)) + (R + 1) * (sqrt(2) * sqrt(1 /
(R + 1)) - 1)
sol = solveset_complex(eq, R)
assert sol == FiniteSet(
*[(S(5) / 3 + 40 / (3 * (251 + 3 * sqrt(111) * I)**(S(1) / 3)) +
(251 + 3 * sqrt(111) * I)**(S(1) / 3) / 3, ),
((-160 + (1 + sqrt(3) * I) *
(10 - (1 + sqrt(3) * I) * (251 + 3 * sqrt(111) * I)**(S(1) / 3)) *
(251 + 3 * sqrt(111) * I)**(S(1) / 3)) /
Mul(6, (1 + sqrt(3) * I), (251 + 3 * sqrt(111) * I)**(S(1) / 3),
evaluate=False), )])
eq = -sqrt((m - q)**2 + (-m / (2 * q) + S(1) / 2)**2) + sqrt(
(-m**2 / 2 - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 - S(1) / 4)**2 +
(m**2 / 2 - m - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 -
S(1) / 4)**2)
assert solveset_real(eq, q) == FiniteSet(
m**2 / 2 - sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 - S(1) / 4,
m**2 / 2 + sqrt(4 * m**4 - 4 * m**2 + 8 * m + 1) / 4 - S(1) / 4)
def test_solve_only_exp_1():
y = Symbol('y', positive=True, finite=True)
assert solveset_real(exp(x) - y, x) == FiniteSet(log(y))
assert solveset_real(exp(x) + exp(-x) - 4, x) == \
FiniteSet(log(-sqrt(3) + 2), log(sqrt(3) + 2))
assert solveset_real(exp(x) + exp(-x) - y, x) != S.EmptySet
def test_solve_lambert():
assert solveset_real(x*exp(x) - 1, x) == FiniteSet(LambertW(1))
assert solveset_real(x + 2**x, x) == \
FiniteSet(-LambertW(log(2))/log(2))
# issue 4739
assert solveset_real(exp(log(5)*x) - 2**x, x) == FiniteSet(0)
ans = solveset_real(3*x + 5 + 2**(-5*x + 3), x)
assert ans == FiniteSet(-Rational(5, 3) +
LambertW(-10240*2**(S(1)/3)*log(2)/3)/(5*log(2)))
eq = 2*(3*x + 4)**5 - 6*7**(3*x + 9)
result = solveset_real(eq, x)
ans = FiniteSet((log(2401) +
5*LambertW(-log(7**(7*3**Rational(1, 5)/5))))/(3*log(7))/-1)
assert result == ans
assert solveset_real(eq.expand(), x) == result
assert solveset_real(5*x - 1 + 3*exp(2 - 7*x), x) == \
FiniteSet(Rational(1, 5) + LambertW(-21*exp(Rational(3, 5))/5)/7)
assert solveset_real(2*x + 5 + log(3*x - 2), x) == \
FiniteSet(Rational(2, 3) + LambertW(2*exp(-Rational(19, 3))/3)/2)
assert solveset_real(3*x + log(4*x), x) == \
FiniteSet(LambertW(Rational(3, 4))/3)
assert solveset_complex(x**z*y**z - 2, z) == \
FiniteSet(log(2)/(log(x) + log(y)))
assert solveset_real(x**x - 2) == FiniteSet(exp(LambertW(log(2))))
a = Symbol('a')
assert solveset_real(-a*x + 2*x*log(x), x) == FiniteSet(exp(a/2))
a = Symbol('a', real=True)
assert solveset_real(a/x + exp(x/2), x) == \
FiniteSet(2*LambertW(-a/2))
assert solveset_real((a/x + exp(x/2)).diff(x), x) == \
FiniteSet(4*LambertW(sqrt(2)*sqrt(a)/4))
assert solveset_real(1/(1/x - y + exp(y)), x) == EmptySet()
# coverage test
p = Symbol('p', positive=True)
w = Symbol('w')
assert solveset_real((1/p + 1)**(p + 1), p) == EmptySet()
assert solveset_real(tanh(x + 3)*tanh(x - 3) - 1, x) == EmptySet()
assert solveset_real(2*x**w - 4*y**w, w) == \
solveset_real((x/y)**w - 2, w)
assert solveset_real((x**2 - 2*x + 1).subs(x, log(x) + 3*x), x) == \
FiniteSet(LambertW(3*S.Exp1)/3)
assert solveset_real((x**2 - 2*x + 1).subs(x, (log(x) + 3*x)**2 - 1), x) == \
FiniteSet(LambertW(3*exp(-sqrt(2)))/3, LambertW(3*exp(sqrt(2)))/3)
assert solveset_real((x**2 - 2*x - 2).subs(x, log(x) + 3*x), x) == \
FiniteSet(LambertW(3*exp(1 + sqrt(3)))/3, LambertW(3*exp(-sqrt(3) + 1))/3)
assert solveset_real(x*log(x) + 3*x + 1, x) == \
FiniteSet(exp(-3 + LambertW(-exp(3))))
eq = (x*exp(x) - 3).subs(x, x*exp(x))
assert solveset_real(eq, x) == \
FiniteSet(LambertW(3*exp(-LambertW(3))))
assert solveset_real(3*log(a**(3*x + 5)) + a**(3*x + 5), x) == \
FiniteSet(-((log(a**5) + LambertW(S(1)/3))/(3*log(a))))
p = symbols('p', positive=True)
assert solveset_real(3*log(p**(3*x + 5)) + p**(3*x + 5), x) == \
FiniteSet(
log((-3**(S(1)/3) - 3**(S(5)/6)*I)*LambertW(S(1)/3)**(S(1)/3)/(2*p**(S(5)/3)))/log(p),
log((-3**(S(1)/3) + 3**(S(5)/6)*I)*LambertW(S(1)/3)**(S(1)/3)/(2*p**(S(5)/3)))/log(p),
log((3*LambertW(S(1)/3)/p**5)**(1/(3*log(p)))),) # checked numerically
# check collection
b = Symbol('b')
eq = 3*log(a**(3*x + 5)) + b*log(a**(3*x + 5)) + a**(3*x + 5)
assert solveset_real(eq, x) == FiniteSet(
-((log(a**5) + LambertW(1/(b + 3)))/(3*log(a))))
# issue 4271
assert solveset_real((a/x + exp(x/2)).diff(x, 2), x) == FiniteSet(
6*LambertW((-1)**(S(1)/3)*a**(S(1)/3)/3))
assert solveset_real(x**3 - 3**x, x) == \
FiniteSet(-3/log(3)*LambertW(-log(3)/3))
assert solveset_real(x**2 - 2**x, x) == FiniteSet(2)
assert solveset_real(-x**2 + 2**x, x) == FiniteSet(2)
assert solveset_real(3**cos(x) - cos(x)**3) == FiniteSet(
acos(-3*LambertW(-log(3)/3)/log(3)))
assert solveset_real(4**(x/2) - 2**(x/3), x) == FiniteSet(0)
assert solveset_real(5**(x/2) - 2**(x/3), x) == FiniteSet(0)
b = sqrt(6)*sqrt(log(2))/sqrt(log(5))
assert solveset_real(5**(x/2) - 2**(3/x), x) == FiniteSet(-b, b)
def test_solve_invalid_sol():
assert 0 not in solveset_real(sin(x) / x, x)
assert 0 not in solveset_complex((exp(x) - 1) / x, x)
def test_solve_lambert():
assert solveset_real(x * exp(x) - 1, x) == FiniteSet(LambertW(1))
assert solveset_real(x + 2**x, x) == \
FiniteSet(-LambertW(log(2))/log(2))
# issue 4739
assert solveset_real(exp(log(5) * x) - 2**x, x) == FiniteSet(0)
ans = solveset_real(3 * x + 5 + 2**(-5 * x + 3), x)
assert ans == FiniteSet(-Rational(5, 3) +
LambertW(-10240 * 2**(S(1) / 3) * log(2) / 3) /
(5 * log(2)))
eq = 2 * (3 * x + 4)**5 - 6 * 7**(3 * x + 9)
result = solveset_real(eq, x)
ans = FiniteSet(
(log(2401) + 5 * LambertW(-log(7**(7 * 3**Rational(1, 5) / 5)))) /
(3 * log(7)) / -1)
assert result == ans
assert solveset_real(eq.expand(), x) == result
assert solveset_real(5*x - 1 + 3*exp(2 - 7*x), x) == \
FiniteSet(Rational(1, 5) + LambertW(-21*exp(Rational(3, 5))/5)/7)
assert solveset_real(2*x + 5 + log(3*x - 2), x) == \
FiniteSet(Rational(2, 3) + LambertW(2*exp(-Rational(19, 3))/3)/2)
assert solveset_real(3*x + log(4*x), x) == \
FiniteSet(LambertW(Rational(3, 4))/3)
assert solveset_complex(x**z*y**z - 2, z) == \
FiniteSet(log(2)/(log(x) + log(y)))
assert solveset_real(x**x - 2) == FiniteSet(exp(LambertW(log(2))))
a = Symbol('a')
assert solveset_real(-a * x + 2 * x * log(x), x) == FiniteSet(exp(a / 2))
a = Symbol('a', real=True)
assert solveset_real(a/x + exp(x/2), x) == \
FiniteSet(2*LambertW(-a/2))
assert solveset_real((a/x + exp(x/2)).diff(x), x) == \
FiniteSet(4*LambertW(sqrt(2)*sqrt(a)/4))
assert solveset_real(1 / (1 / x - y + exp(y)), x) == EmptySet()
# coverage test
p = Symbol('p', positive=True)
w = Symbol('w')
assert solveset_real((1 / p + 1)**(p + 1), p) == EmptySet()
assert solveset_real(tanh(x + 3) * tanh(x - 3) - 1, x) == EmptySet()
assert solveset_real(2*x**w - 4*y**w, w) == \
solveset_real((x/y)**w - 2, w)
assert solveset_real((x**2 - 2*x + 1).subs(x, log(x) + 3*x), x) == \
FiniteSet(LambertW(3*S.Exp1)/3)
assert solveset_real((x**2 - 2*x + 1).subs(x, (log(x) + 3*x)**2 - 1), x) == \
FiniteSet(LambertW(3*exp(-sqrt(2)))/3, LambertW(3*exp(sqrt(2)))/3)
assert solveset_real((x**2 - 2*x - 2).subs(x, log(x) + 3*x), x) == \
FiniteSet(LambertW(3*exp(1 + sqrt(3)))/3, LambertW(3*exp(-sqrt(3) + 1))/3)
assert solveset_real(x*log(x) + 3*x + 1, x) == \
FiniteSet(exp(-3 + LambertW(-exp(3))))
eq = (x * exp(x) - 3).subs(x, x * exp(x))
assert solveset_real(eq, x) == \
FiniteSet(LambertW(3*exp(-LambertW(3))))
assert solveset_real(3*log(a**(3*x + 5)) + a**(3*x + 5), x) == \
FiniteSet(-((log(a**5) + LambertW(S(1)/3))/(3*log(a))))
p = symbols('p', positive=True)
assert solveset_real(3*log(p**(3*x + 5)) + p**(3*x + 5), x) == \
FiniteSet(
log((-3**(S(1)/3) - 3**(S(5)/6)*I)*LambertW(S(1)/3)**(S(1)/3)/(2*p**(S(5)/3)))/log(p),
log((-3**(S(1)/3) + 3**(S(5)/6)*I)*LambertW(S(1)/3)**(S(1)/3)/(2*p**(S(5)/3)))/log(p),
log((3*LambertW(S(1)/3)/p**5)**(1/(3*log(p)))),) # checked numerically
# check collection
b = Symbol('b')
eq = 3 * log(a**(3 * x + 5)) + b * log(a**(3 * x + 5)) + a**(3 * x + 5)
assert solveset_real(
eq,
x) == FiniteSet(-((log(a**5) + LambertW(1 / (b + 3))) / (3 * log(a))))
# issue 4271
assert solveset_real((a / x + exp(x / 2)).diff(x, 2),
x) == FiniteSet(6 * LambertW(
(-1)**(S(1) / 3) * a**(S(1) / 3) / 3))
assert solveset_real(x**3 - 3**x, x) == \
FiniteSet(-3/log(3)*LambertW(-log(3)/3))
assert solveset_real(x**2 - 2**x, x) == FiniteSet(2)
assert solveset_real(-x**2 + 2**x, x) == FiniteSet(2)
assert solveset_real(3**cos(x) - cos(x)**3) == FiniteSet(
acos(-3 * LambertW(-log(3) / 3) / log(3)))
assert solveset_real(4**(x / 2) - 2**(x / 3), x) == FiniteSet(0)
assert solveset_real(5**(x / 2) - 2**(x / 3), x) == FiniteSet(0)
b = sqrt(6) * sqrt(log(2)) / sqrt(log(5))
assert solveset_real(5**(x / 2) - 2**(3 / x), x) == FiniteSet(-b, b)
def test_solve_only_exp_2():
assert solveset_real(exp(x/y)*exp(-z/y) - 2, y) == \
FiniteSet((x - z)/log(2))
assert solveset_real(sqrt(exp(x)) + sqrt(exp(-x)) - 4, x) == \
FiniteSet(2*log(-sqrt(3) + 2), 2*log(sqrt(3) + 2))
def test_atan2():
# The .inverse() method on atan2 works only if x.is_real is True and the
# second argument is a real constant
assert solveset_real(atan2(x, 2) - pi / 3, x) == FiniteSet(2 * sqrt(3))
def test_solve_only_exp_1():
y = Symbol('y', positive=True, finite=True)
assert solveset_real(exp(x) - y, x) == FiniteSet(log(y))
assert solveset_real(exp(x) + exp(-x) - 4, x) == \
FiniteSet(log(-sqrt(3) + 2), log(sqrt(3) + 2))
assert solveset_real(exp(x) + exp(-x) - y, x) != S.EmptySet
def test_units():
assert solveset_real(1 / x - 1 / (2 * cm), x) == FiniteSet(2 * cm)
def test_poly_gens():
assert solveset_real(4**(2*(x**2) + 2*x) - 8, x) == \
FiniteSet(-Rational(3, 2), S.Half)
def test_solve_only_exp_2():
assert solveset_real(exp(x/y)*exp(-z/y) - 2, y) == \
FiniteSet((x - z)/log(2))
assert solveset_real(sqrt(exp(x)) + sqrt(exp(-x)) - 4, x) == \
FiniteSet(2*log(-sqrt(3) + 2), 2*log(sqrt(3) + 2))
def test_solveset_real_log():
assert solveset_real(log((x-1)*(x+1)), x) == \
FiniteSet(sqrt(2), -sqrt(2))
def test_atan2():
# The .inverse() method on atan2 works only if x.is_real is True and the
# second argument is a real constant
assert solveset_real(atan2(x, 2) - pi/3, x) == FiniteSet(2*sqrt(3))
def test_solveset_real_rational():
"""Test solveset_real for rational functions"""
assert solveset_real((x - y**3) / ((y**2)*sqrt(1 - y**2)), x) \
== FiniteSet(y**3)
# issue 4486
assert solveset_real(2 * x / (x + 2) - 1, x) == FiniteSet(2)
def test_solve_invalid_sol():
assert 0 not in solveset_real(sin(x)/x, x)
assert 0 not in solveset_complex((exp(x) - 1)/x, x)
def test_uselogcombine_2():
eq = z - log(x) + log(y / (x * (-1 + y**2 / x**2)))
assert solveset_real(eq, x) == \
FiniteSet(-sqrt(y*(y - exp(z))), sqrt(y*(y - exp(z))))
def intersection_sets(self, other): # noqa:F811
from sympy.solvers.diophantine import diophantine
# Only handle the straight-forward univariate case
if (len(self.lamda.variables) > 1
or self.lamda.signature != self.lamda.variables):
return None
base_set = self.base_sets[0]
# Intersection between ImageSets with Integers as base set
# For {f(n) : n in Integers} & {g(m) : m in Integers} we solve the
# diophantine equations f(n)=g(m).
# If the solutions for n are {h(t) : t in Integers} then we return
# {f(h(t)) : t in integers}.
# If the solutions for n are {n_1, n_2, ..., n_k} then we return
# {f(n_i) : 1 <= i <= k}.
if base_set is S.Integers:
gm = None
if isinstance(other, ImageSet) and other.base_sets == (S.Integers, ):
gm = other.lamda.expr
var = other.lamda.variables[0]
# Symbol of second ImageSet lambda must be distinct from first
m = Dummy('m')
gm = gm.subs(var, m)
elif other is S.Integers:
m = gm = Dummy('m')
if gm is not None:
fn = self.lamda.expr
n = self.lamda.variables[0]
try:
solns = list(diophantine(fn - gm, syms=(n, m), permute=True))
except (TypeError, NotImplementedError):
# TypeError if equation not polynomial with rational coeff.
# NotImplementedError if correct format but no solver.
return
# 3 cases are possible for solns:
# - empty set,
# - one or more parametric (infinite) solutions,
# - a finite number of (non-parametric) solution couples.
# Among those, there is one type of solution set that is
# not helpful here: multiple parametric solutions.
if len(solns) == 0:
return EmptySet
elif any(not isinstance(s, int) and s.free_symbols
for tupl in solns for s in tupl):
if len(solns) == 1:
soln, solm = solns[0]
(t, ) = soln.free_symbols
expr = fn.subs(n, soln.subs(t, n)).expand()
return imageset(Lambda(n, expr), S.Integers)
else:
return
else:
return FiniteSet(*(fn.subs(n, s[0]) for s in solns))
if other == S.Reals:
from sympy.solvers.solveset import solveset_real
from sympy.core.function import expand_complex
f = self.lamda.expr
n = self.lamda.variables[0]
n_ = Dummy(n.name, real=True)
f_ = f.subs(n, n_)
re, im = f_.as_real_imag()
im = expand_complex(im)
re = re.subs(n_, n)
im = im.subs(n_, n)
ifree = im.free_symbols
lam = Lambda(n, re)
if not im:
# allow re-evaluation
# of self in this case to make
# the result canonical
pass
elif im.is_zero is False:
return S.EmptySet
elif ifree != {n}:
return None
else:
# univarite imaginary part in same variable
base_set = base_set.intersect(solveset_real(im, n))
return imageset(lam, base_set)
elif isinstance(other, Interval):
from sympy.solvers.solveset import (invert_real, invert_complex,
solveset)
f = self.lamda.expr
n = self.lamda.variables[0]
new_inf, new_sup = None, None
new_lopen, new_ropen = other.left_open, other.right_open
if f.is_real:
inverter = invert_real
else:
inverter = invert_complex
g1, h1 = inverter(f, other.inf, n)
g2, h2 = inverter(f, other.sup, n)
if all(isinstance(i, FiniteSet) for i in (h1, h2)):
if g1 == n:
if len(h1) == 1:
new_inf = h1.args[0]
if g2 == n:
if len(h2) == 1:
new_sup = h2.args[0]
# TODO: Design a technique to handle multiple-inverse
# functions
# Any of the new boundary values cannot be determined
if any(i is None for i in (new_sup, new_inf)):
return
range_set = S.EmptySet
if all(i.is_real for i in (new_sup, new_inf)):
# this assumes continuity of underlying function
# however fixes the case when it is decreasing
if new_inf > new_sup:
new_inf, new_sup = new_sup, new_inf
new_interval = Interval(new_inf, new_sup, new_lopen, new_ropen)
range_set = base_set.intersect(new_interval)
else:
if other.is_subset(S.Reals):
solutions = solveset(f, n, S.Reals)
if not isinstance(range_set, (ImageSet, ConditionSet)):
range_set = solutions.intersect(other)
else:
return
if range_set is S.EmptySet:
return S.EmptySet
elif isinstance(range_set,
Range) and range_set.size is not S.Infinity:
range_set = FiniteSet(*list(range_set))
if range_set is not None:
return imageset(Lambda(n, f), range_set)
return
else:
return
def test_real_imag_splitting():
a, b = symbols('a b', real=True, finite=True)
assert solveset_real(sqrt(a**2 - b**2) - 3, a) == \
FiniteSet(-sqrt(b**2 + 9), sqrt(b**2 + 9))
assert solveset_real(sqrt(a**2 + b**2) - 3, a) != \
S.EmptySet