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from sympy.assumptions.ask import (Q, ask)from sympy.core.add import Addfrom sympy.core.containers import Tuplefrom sympy.core.function import (Derivative, Function, diff)from sympy.core.mul import Mulfrom sympy.core import (GoldenRatio, TribonacciConstant)from sympy.core.numbers import (E, Float, I, Rational, oo, pi)from sympy.core.relational import (Eq, Gt, Lt, Ne)from sympy.core.singleton import Sfrom sympy.core.symbol import (Dummy, Symbol, Wild, symbols)from sympy.core.sympify import sympifyfrom sympy.functions.combinatorial.factorials import binomialfrom sympy.functions.elementary.complexes import (Abs, arg, conjugate, im, re)from sympy.functions.elementary.exponential import (LambertW, exp, log)from sympy.functions.elementary.hyperbolic import (atanh, cosh, sinh, tanh)from sympy.functions.elementary.miscellaneous import (cbrt, root, sqrt)from sympy.functions.elementary.piecewise import Piecewisefrom sympy.functions.elementary.trigonometric import (acos, asin, atan, atan2, cos, sec, sin, tan)from sympy.functions.special.error_functions import (erf, erfc, erfcinv, erfinv)from sympy.integrals.integrals import Integralfrom sympy.logic.boolalg import (And, Or)from sympy.matrices.dense import Matrixfrom sympy.matrices import SparseMatrixfrom sympy.polys.polytools import Polyfrom sympy.printing.str import sstrfrom sympy.simplify.radsimp import denomfrom sympy.solvers.solvers import (nsolve, solve, solve_linear)
from sympy.core.function import nfloatfrom sympy.solvers import solve_linear_system, solve_linear_system_LU, \ solve_undetermined_coeffsfrom sympy.solvers.bivariate import _filtered_gens, _solve_lambert, _lambertfrom sympy.solvers.solvers import _invert, unrad, checksol, posify, _ispow, \ det_quick, det_perm, det_minor, _simple_dens, denoms
from sympy.physics.units import cmfrom sympy.polys.rootoftools import CRootOf
from sympy.testing.pytest import slow, XFAIL, SKIP, raisesfrom sympy.core.random import verify_numerically as tn
from sympy.abc import a, b, c, d, e, k, h, p, x, y, z, t, q, m, R
def NS(e, n=15, **options): return sstr(sympify(e).evalf(n, **options), full_prec=True)
def test_swap_back(): f, g = map(Function, 'fg') fx, gx = f(x), g(x) assert solve([fx + y - 2, fx - gx - 5], fx, y, gx) == \ {fx: gx + 5, y: -gx - 3} assert solve(fx + gx*x - 2, [fx, gx], dict=True)[0] == {fx: 2, gx: 0} assert solve(fx + gx**2*x - y, [fx, gx], dict=True) == [{fx: y - gx**2*x}] assert solve([f(1) - 2, x + 2], dict=True) == [{x: -2, f(1): 2}]
def guess_solve_strategy(eq, symbol): try: solve(eq, symbol) return True except (TypeError, NotImplementedError): return False
def test_guess_poly(): # polynomial equations assert guess_solve_strategy( S(4), x ) # == GS_POLY assert guess_solve_strategy( x, x ) # == GS_POLY assert guess_solve_strategy( x + a, x ) # == GS_POLY assert guess_solve_strategy( 2*x, x ) # == GS_POLY assert guess_solve_strategy( x + sqrt(2), x) # == GS_POLY assert guess_solve_strategy( x + 2**Rational(1, 4), x) # == GS_POLY assert guess_solve_strategy( x**2 + 1, x ) # == GS_POLY assert guess_solve_strategy( x**2 - 1, x ) # == GS_POLY assert guess_solve_strategy( x*y + y, x ) # == GS_POLY assert guess_solve_strategy( x*exp(y) + y, x) # == GS_POLY assert guess_solve_strategy( (x - y**3)/(y**2*sqrt(1 - y**2)), x) # == GS_POLY
def test_guess_poly_cv(): # polynomial equations via a change of variable assert guess_solve_strategy( sqrt(x) + 1, x ) # == GS_POLY_CV_1 assert guess_solve_strategy( x**Rational(1, 3) + sqrt(x) + 1, x ) # == GS_POLY_CV_1 assert guess_solve_strategy( 4*x*(1 - sqrt(x)), x ) # == GS_POLY_CV_1
# polynomial equation multiplying both sides by x**n assert guess_solve_strategy( x + 1/x + y, x ) # == GS_POLY_CV_2
def test_guess_rational_cv(): # rational functions assert guess_solve_strategy( (x + 1)/(x**2 + 2), x) # == GS_RATIONAL assert guess_solve_strategy( (x - y**3)/(y**2*sqrt(1 - y**2)), y) # == GS_RATIONAL_CV_1
# rational functions via the change of variable y -> x**n assert guess_solve_strategy( (sqrt(x) + 1)/(x**Rational(1, 3) + sqrt(x) + 1), x ) \ #== GS_RATIONAL_CV_1
def test_guess_transcendental(): #transcendental functions assert guess_solve_strategy( exp(x) + 1, x ) # == GS_TRANSCENDENTAL assert guess_solve_strategy( 2*cos(x) - y, x ) # == GS_TRANSCENDENTAL assert guess_solve_strategy( exp(x) + exp(-x) - y, x ) # == GS_TRANSCENDENTAL assert guess_solve_strategy(3**x - 10, x) # == GS_TRANSCENDENTAL assert guess_solve_strategy(-3**x + 10, x) # == GS_TRANSCENDENTAL
assert guess_solve_strategy(a*x**b - y, x) # == GS_TRANSCENDENTAL
def test_solve_args(): # equation container, issue 5113 ans = {x: -3, y: 1} eqs = (x + 5*y - 2, -3*x + 6*y - 15) assert all(solve(container(eqs), x, y) == ans for container in (tuple, list, set, frozenset)) assert solve(Tuple(*eqs), x, y) == ans # implicit symbol to solve for assert set(solve(x**2 - 4)) == {S(2), -S(2)} assert solve([x + y - 3, x - y - 5]) == {x: 4, y: -1} assert solve(x - exp(x), x, implicit=True) == [exp(x)] # no symbol to solve for assert solve(42) == solve(42, x) == [] assert solve([1, 2]) == [] assert solve([sqrt(2)],[x]) == [] # duplicate symbols removed assert solve((x - 3, y + 2), x, y, x) == {x: 3, y: -2} # unordered symbols # only 1 assert solve(y - 3, {y}) == [3] # more than 1 assert solve(y - 3, {x, y}) == [{y: 3}] # multiple symbols: take the first linear solution+ # - return as tuple with values for all requested symbols assert solve(x + y - 3, [x, y]) == [(3 - y, y)] # - unless dict is True assert solve(x + y - 3, [x, y], dict=True) == [{x: 3 - y}] # - or no symbols are given assert solve(x + y - 3) == [{x: 3 - y}] # multiple symbols might represent an undetermined coefficients system assert solve(a + b*x - 2, [a, b]) == {a: 2, b: 0} args = (a + b)*x - b**2 + 2, a, b assert solve(*args) == \ [(-sqrt(2), sqrt(2)), (sqrt(2), -sqrt(2))] assert solve(*args, set=True) == \ ([a, b], {(-sqrt(2), sqrt(2)), (sqrt(2), -sqrt(2))}) assert solve(*args, dict=True) == \ [{b: sqrt(2), a: -sqrt(2)}, {b: -sqrt(2), a: sqrt(2)}] eq = a*x**2 + b*x + c - ((x - h)**2 + 4*p*k)/4/p flags = dict(dict=True) assert solve(eq, [h, p, k], exclude=[a, b, c], **flags) == \ [{k: c - b**2/(4*a), h: -b/(2*a), p: 1/(4*a)}] flags.update(dict(simplify=False)) assert solve(eq, [h, p, k], exclude=[a, b, c], **flags) == \ [{k: (4*a*c - b**2)/(4*a), h: -b/(2*a), p: 1/(4*a)}] # failing undetermined system assert solve(a*x + b**2/(x + 4) - 3*x - 4/x, a, b, dict=True) == \ [{a: (-b**2*x + 3*x**3 + 12*x**2 + 4*x + 16)/(x**2*(x + 4))}] # failed single equation assert solve(1/(1/x - y + exp(y))) == [] raises( NotImplementedError, lambda: solve(exp(x) + sin(x) + exp(y) + sin(y))) # failed system # -- when no symbols given, 1 fails assert solve([y, exp(x) + x]) == {x: -LambertW(1), y: 0} # both fail assert solve( (exp(x) - x, exp(y) - y)) == {x: -LambertW(-1), y: -LambertW(-1)} # -- when symbols given assert solve([y, exp(x) + x], x, y) == {y: 0, x: -LambertW(1)} # symbol is a number assert solve(x**2 - pi, pi) == [x**2] # no equations assert solve([], [x]) == [] # overdetermined system # - nonlinear assert solve([(x + y)**2 - 4, x + y - 2]) == [{x: -y + 2}] # - linear assert solve((x + y - 2, 2*x + 2*y - 4)) == {x: -y + 2} # When one or more args are Boolean assert solve(Eq(x**2, 0.0)) == [0] # issue 19048 assert solve([True, Eq(x, 0)], [x], dict=True) == [{x: 0}] assert solve([Eq(x, x), Eq(x, 0), Eq(x, x+1)], [x], dict=True) == [] assert not solve([Eq(x, x+1), x < 2], x) assert solve([Eq(x, 0), x+1<2]) == Eq(x, 0) assert solve([Eq(x, x), Eq(x, x+1)], x) == [] assert solve(True, x) == [] assert solve([x - 1, False], [x], set=True) == ([], set())
def test_solve_polynomial1(): assert solve(3*x - 2, x) == [Rational(2, 3)] assert solve(Eq(3*x, 2), x) == [Rational(2, 3)]
assert set(solve(x**2 - 1, x)) == {-S.One, S.One} assert set(solve(Eq(x**2, 1), x)) == {-S.One, S.One}
assert solve(x - y**3, x) == [y**3] rx = root(x, 3) assert solve(x - y**3, y) == [ rx, -rx/2 - sqrt(3)*I*rx/2, -rx/2 + sqrt(3)*I*rx/2] a11, a12, a21, a22, b1, b2 = symbols('a11,a12,a21,a22,b1,b2')
assert solve([a11*x + a12*y - b1, a21*x + a22*y - b2], x, y) == \ { x: (a22*b1 - a12*b2)/(a11*a22 - a12*a21), y: (a11*b2 - a21*b1)/(a11*a22 - a12*a21), }
solution = {y: S.Zero, x: S.Zero}
assert solve((x - y, x + y), x, y ) == solution assert solve((x - y, x + y), (x, y)) == solution assert solve((x - y, x + y), [x, y]) == solution
assert set(solve(x**3 - 15*x - 4, x)) == { -2 + 3**S.Half, S(4), -2 - 3**S.Half }
assert set(solve((x**2 - 1)**2 - a, x)) == \ {sqrt(1 + sqrt(a)), -sqrt(1 + sqrt(a)), sqrt(1 - sqrt(a)), -sqrt(1 - sqrt(a))}
def test_solve_polynomial2(): assert solve(4, x) == []
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 solve( sqrt(x) - 1, x) == [1] assert solve( sqrt(x) - 2, x) == [4] assert solve( x**Rational(1, 4) - 2, x) == [16] assert solve( x**Rational(1, 3) - 3, x) == [27] assert solve(sqrt(x) + x**Rational(1, 3) + x**Rational(1, 4), x) == [0]
def test_solve_polynomial_cv_1b(): assert set(solve(4*x*(1 - a*sqrt(x)), x)) == {S.Zero, 1/a**2} assert set(solve(x*(root(x, 3) - 3), x)) == {S.Zero, S(27)}
def test_solve_polynomial_cv_2(): """
Test for solving on equations that can be converted to a polynomial equation multiplying both sides of the equation by x**m """
assert solve(x + 1/x - 1, x) in \ [[ S.Half + I*sqrt(3)/2, S.Half - I*sqrt(3)/2], [ S.Half - I*sqrt(3)/2, S.Half + I*sqrt(3)/2]]
def test_quintics_1(): f = x**5 - 110*x**3 - 55*x**2 + 2310*x + 979 s = solve(f, check=False) for r in s: res = f.subs(x, r.n()).n() assert tn(res, 0)
f = x**5 - 15*x**3 - 5*x**2 + 10*x + 20 s = solve(f) for r in s: assert r.func == CRootOf
# if one uses solve to get the roots of a polynomial that has a CRootOf # solution, make sure that the use of nfloat during the solve process # doesn't fail. Note: if you want numerical solutions to a polynomial # it is *much* faster to use nroots to get them than to solve the # equation only to get RootOf solutions which are then numerically # evaluated. So for eq = x**5 + 3*x + 7 do Poly(eq).nroots() rather # than [i.n() for i in solve(eq)] to get the numerical roots of eq. assert nfloat(solve(x**5 + 3*x**3 + 7)[0], exponent=False) == \ CRootOf(x**5 + 3*x**3 + 7, 0).n()
def test_quintics_2(): f = x**5 + 15*x + 12 s = solve(f, check=False) for r in s: res = f.subs(x, r.n()).n() assert tn(res, 0)
f = x**5 - 15*x**3 - 5*x**2 + 10*x + 20 s = solve(f) for r in s: assert r.func == CRootOf
assert solve(x**5 - 6*x**3 - 6*x**2 + x - 6) == [ CRootOf(x**5 - 6*x**3 - 6*x**2 + x - 6, 0), CRootOf(x**5 - 6*x**3 - 6*x**2 + x - 6, 1), CRootOf(x**5 - 6*x**3 - 6*x**2 + x - 6, 2), CRootOf(x**5 - 6*x**3 - 6*x**2 + x - 6, 3), CRootOf(x**5 - 6*x**3 - 6*x**2 + x - 6, 4)]
def test_quintics_3(): y = x**5 + x**3 - 2**Rational(1, 3) assert solve(y) == solve(-y) == []
def test_highorder_poly(): # just testing that the uniq generator is unpacked sol = solve(x**6 - 2*x + 2) assert all(isinstance(i, CRootOf) for i in sol) and len(sol) == 6
def test_solve_rational(): """Test solve for rational functions""" assert solve( ( x - y**3 )/( (y**2)*sqrt(1 - y**2) ), x) == [y**3]
def test_solve_conjugate(): """Test solve for simple conjugate functions""" assert solve(conjugate(x) -3 + I) == [3 + I]
def test_solve_nonlinear(): assert solve(x**2 - y**2, x, y, dict=True) == [{x: -y}, {x: y}] assert solve(x**2 - y**2/exp(x), y, x, dict=True) == [{y: -x*sqrt(exp(x))}, {y: x*sqrt(exp(x))}]
def test_issue_8666(): x = symbols('x') assert solve(Eq(x**2 - 1/(x**2 - 4), 4 - 1/(x**2 - 4)), x) == [] assert solve(Eq(x + 1/x, 1/x), x) == []
def test_issue_7228(): assert solve(4**(2*(x**2) + 2*x) - 8, x) == [Rational(-3, 2), S.Half]
def test_issue_7190(): assert solve(log(x-3) + log(x+3), x) == [sqrt(10)]
def test_issue_21004(): x = symbols('x') f = x/sqrt(x**2+1) f_diff = f.diff(x) assert solve(f_diff, x) == []
def test_linear_system(): x, y, z, t, n = symbols('x, y, z, t, n')
assert solve([x - 1, x - y, x - 2*y, y - 1], [x, y]) == []
assert solve([x - 1, x - y, x - 2*y, x - 1], [x, y]) == [] assert solve([x - 1, x - 1, x - y, x - 2*y], [x, y]) == []
assert solve([x + 5*y - 2, -3*x + 6*y - 15], x, y) == {x: -3, y: 1}
M = Matrix([[0, 0, n*(n + 1), (n + 1)**2, 0], [n + 1, n + 1, -2*n - 1, -(n + 1), 0], [-1, 0, 1, 0, 0]])
assert solve_linear_system(M, x, y, z, t) == \ {x: t*(-n-1)/n, z: t*(-n-1)/n, y: 0}
assert solve([x + y + z + t, -z - t], x, y, z, t) == {x: -y, z: -t}
@XFAILdef test_linear_system_xfail(): # https://github.com/sympy/sympy/issues/6420 M = Matrix([[0, 15.0, 10.0, 700.0], [1, 1, 1, 100.0], [0, 10.0, 5.0, 200.0], [-5.0, 0, 0, 0 ]])
assert solve_linear_system(M, x, y, z) == {x: 0, y: -60.0, z: 160.0}
def test_linear_system_function(): a = Function('a') assert solve([a(0, 0) + a(0, 1) + a(1, 0) + a(1, 1), -a(1, 0) - a(1, 1)], a(0, 0), a(0, 1), a(1, 0), a(1, 1)) == {a(1, 0): -a(1, 1), a(0, 0): -a(0, 1)}
def test_linear_system_symbols_doesnt_hang_1():
def _mk_eqs(wy): # Equations for fitting a wy*2 - 1 degree polynomial between two points, # at end points derivatives are known up to order: wy - 1 order = 2*wy - 1 x, x0, x1 = symbols('x, x0, x1', real=True) y0s = symbols('y0_:{}'.format(wy), real=True) y1s = symbols('y1_:{}'.format(wy), real=True) c = symbols('c_:{}'.format(order+1), real=True)
expr = sum([coeff*x**o for o, coeff in enumerate(c)]) eqs = [] for i in range(wy): eqs.append(expr.diff(x, i).subs({x: x0}) - y0s[i]) eqs.append(expr.diff(x, i).subs({x: x1}) - y1s[i]) return eqs, c
# # The purpose of this test is just to see that these calls don't hang. The # expressions returned are complicated so are not included here. Testing # their correctness takes longer than solving the system. #
for n in range(1, 7+1): eqs, c = _mk_eqs(n) solve(eqs, c)
def test_linear_system_symbols_doesnt_hang_2():
M = Matrix([ [66, 24, 39, 50, 88, 40, 37, 96, 16, 65, 31, 11, 37, 72, 16, 19, 55, 37, 28, 76], [10, 93, 34, 98, 59, 44, 67, 74, 74, 94, 71, 61, 60, 23, 6, 2, 57, 8, 29, 78], [19, 91, 57, 13, 64, 65, 24, 53, 77, 34, 85, 58, 87, 39, 39, 7, 36, 67, 91, 3], [74, 70, 15, 53, 68, 43, 86, 83, 81, 72, 25, 46, 67, 17, 59, 25, 78, 39, 63, 6], [69, 40, 67, 21, 67, 40, 17, 13, 93, 44, 46, 89, 62, 31, 30, 38, 18, 20, 12, 81], [50, 22, 74, 76, 34, 45, 19, 76, 28, 28, 11, 99, 97, 82, 8, 46, 99, 57, 68, 35], [58, 18, 45, 88, 10, 64, 9, 34, 90, 82, 17, 41, 43, 81, 45, 83, 22, 88, 24, 39], [42, 21, 70, 68, 6, 33, 64, 81, 83, 15, 86, 75, 86, 17, 77, 34, 62, 72, 20, 24], [ 7, 8, 2, 72, 71, 52, 96, 5, 32, 51, 31, 36, 79, 88, 25, 77, 29, 26, 33, 13], [19, 31, 30, 85, 81, 39, 63, 28, 19, 12, 16, 49, 37, 66, 38, 13, 3, 71, 61, 51], [29, 82, 80, 49, 26, 85, 1, 37, 2, 74, 54, 82, 26, 47, 54, 9, 35, 0, 99, 40], [15, 49, 82, 91, 93, 57, 45, 25, 45, 97, 15, 98, 48, 52, 66, 24, 62, 54, 97, 37], [62, 23, 73, 53, 52, 86, 28, 38, 0, 74, 92, 38, 97, 70, 71, 29, 26, 90, 67, 45], [ 2, 32, 23, 24, 71, 37, 25, 71, 5, 41, 97, 65, 93, 13, 65, 45, 25, 88, 69, 50], [40, 56, 1, 29, 79, 98, 79, 62, 37, 28, 45, 47, 3, 1, 32, 74, 98, 35, 84, 32], [33, 15, 87, 79, 65, 9, 14, 63, 24, 19, 46, 28, 74, 20, 29, 96, 84, 91, 93, 1], [97, 18, 12, 52, 1, 2, 50, 14, 52, 76, 19, 82, 41, 73, 51, 79, 13, 3, 82, 96], [40, 28, 52, 10, 10, 71, 56, 78, 82, 5, 29, 48, 1, 26, 16, 18, 50, 76, 86, 52], [38, 89, 83, 43, 29, 52, 90, 77, 57, 0, 67, 20, 81, 88, 48, 96, 88, 58, 14, 3]])
syms = x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15,x16,x17,x18 = symbols('x:19')
sol = { x0: -S(1967374186044955317099186851240896179)/3166636564687820453598895768302256588, x1: -S(84268280268757263347292368432053826)/791659141171955113399723942075564147, x2: -S(229962957341664730974463872411844965)/1583318282343910226799447884151128294, x3: S(990156781744251750886760432229180537)/6333273129375640907197791536604513176, x4: -S(2169830351210066092046760299593096265)/18999819388126922721593374609813539528, x5: S(4680868883477577389628494526618745355)/9499909694063461360796687304906769764, x6: -S(1590820774344371990683178396480879213)/3166636564687820453598895768302256588, x7: -S(54104723404825537735226491634383072)/339282489073695048599881689460956063, x8: S(3182076494196560075964847771774733847)/6333273129375640907197791536604513176, x9: -S(10870817431029210431989147852497539675)/18999819388126922721593374609813539528, x10: -S(13118019242576506476316318268573312603)/18999819388126922721593374609813539528, x11: -S(5173852969886775824855781403820641259)/4749954847031730680398343652453384882, x12: S(4261112042731942783763341580651820563)/4749954847031730680398343652453384882, x13: -S(821833082694661608993818117038209051)/6333273129375640907197791536604513176, x14: S(906881575107250690508618713632090559)/904753304196520129599684505229216168, x15: -S(732162528717458388995329317371283987)/6333273129375640907197791536604513176, x16: S(4524215476705983545537087360959896817)/9499909694063461360796687304906769764, x17: -S(3898571347562055611881270844646055217)/6333273129375640907197791536604513176, x18: S(7513502486176995632751685137907442269)/18999819388126922721593374609813539528 }
eqs = list(M * Matrix(syms + (1,))) assert solve(eqs, syms) == sol
y = Symbol('y') eqs = list(y * M * Matrix(syms + (1,))) assert solve(eqs, syms) == sol
def test_linear_systemLU(): n = Symbol('n')
M = Matrix([[1, 2, 0, 1], [1, 3, 2*n, 1], [4, -1, n**2, 1]])
assert solve_linear_system_LU(M, [x, y, z]) == {z: -3/(n**2 + 18*n), x: 1 - 12*n/(n**2 + 18*n), y: 6*n/(n**2 + 18*n)}
# Note: multiple solutions exist for some of these equations, so the tests# should be expected to break if the implementation of the solver changes# in such a way that a different branch is chosen
@slowdef test_solve_transcendental(): from sympy.abc import a, b
assert solve(exp(x) - 3, x) == [log(3)] assert set(solve((a*x + b)*(exp(x) - 3), x)) == {-b/a, log(3)} assert solve(cos(x) - y, x) == [-acos(y) + 2*pi, acos(y)] assert solve(2*cos(x) - y, x) == [-acos(y/2) + 2*pi, acos(y/2)] assert solve(Eq(cos(x), sin(x)), x) == [pi/4]
assert set(solve(exp(x) + exp(-x) - y, x)) in [{ log(y/2 - sqrt(y**2 - 4)/2), log(y/2 + sqrt(y**2 - 4)/2), }, { log(y - sqrt(y**2 - 4)) - log(2), log(y + sqrt(y**2 - 4)) - log(2)}, { log(y/2 - sqrt((y - 2)*(y + 2))/2), log(y/2 + sqrt((y - 2)*(y + 2))/2)}] assert solve(exp(x) - 3, x) == [log(3)] assert solve(Eq(exp(x), 3), x) == [log(3)] assert solve(log(x) - 3, x) == [exp(3)] assert solve(sqrt(3*x) - 4, x) == [Rational(16, 3)] assert solve(3**(x + 2), x) == [] assert solve(3**(2 - x), x) == [] assert solve(x + 2**x, x) == [-LambertW(log(2))/log(2)] assert solve(2*x + 5 + log(3*x - 2), x) == \ [Rational(2, 3) + LambertW(2*exp(Rational(-19, 3))/3)/2] assert solve(3*x + log(4*x), x) == [LambertW(Rational(3, 4))/3] assert set(solve((2*x + 8)*(8 + exp(x)), x)) == {S(-4), log(8) + pi*I} eq = 2*exp(3*x + 4) - 3 ans = solve(eq, x) # this generated a failure in flatten assert len(ans) == 3 and all(eq.subs(x, a).n(chop=True) == 0 for a in ans) assert solve(2*log(3*x + 4) - 3, x) == [(exp(Rational(3, 2)) - 4)/3] assert solve(exp(x) + 1, x) == [pi*I]
eq = 2*(3*x + 4)**5 - 6*7**(3*x + 9) result = solve(eq, x) x0 = -log(2401) x1 = 3**Rational(1, 5) x2 = log(7**(7*x1/20)) x3 = sqrt(2) x4 = sqrt(5) x5 = x3*sqrt(x4 - 5) x6 = x4 + 1 x7 = 1/(3*log(7)) x8 = -x4 x9 = x3*sqrt(x8 - 5) x10 = x8 + 1 ans = [x7*(x0 - 5*LambertW(x2*(-x5 + x6))), x7*(x0 - 5*LambertW(x2*(x5 + x6))), x7*(x0 - 5*LambertW(x2*(x10 - x9))), x7*(x0 - 5*LambertW(x2*(x10 + x9))), x7*(x0 - 5*LambertW(-log(7**(7*x1/5))))] assert result == ans, result # it works if expanded, too assert solve(eq.expand(), x) == result
assert solve(z*cos(x) - y, x) == [-acos(y/z) + 2*pi, acos(y/z)] assert solve(z*cos(2*x) - y, x) == [-acos(y/z)/2 + pi, acos(y/z)/2] assert solve(z*cos(sin(x)) - y, x) == [ pi - asin(acos(y/z)), asin(acos(y/z) - 2*pi) + pi, -asin(acos(y/z) - 2*pi), asin(acos(y/z))]
assert solve(z*cos(x), x) == [pi/2, pi*Rational(3, 2)]
# issue 4508 assert solve(y - b*x/(a + x), x) in [[-a*y/(y - b)], [a*y/(b - y)]] assert solve(y - b*exp(a/x), x) == [a/log(y/b)] # issue 4507 assert solve(y - b/(1 + a*x), x) in [[(b - y)/(a*y)], [-((y - b)/(a*y))]] # issue 4506 assert solve(y - a*x**b, x) == [(y/a)**(1/b)] # issue 4505 assert solve(z**x - y, x) == [log(y)/log(z)] # issue 4504 assert solve(2**x - 10, x) == [1 + log(5)/log(2)] # issue 6744 assert solve(x*y) == [{x: 0}, {y: 0}] assert solve([x*y]) == [{x: 0}, {y: 0}] assert solve(x**y - 1) == [{x: 1}, {y: 0}] assert solve([x**y - 1]) == [{x: 1}, {y: 0}] assert solve(x*y*(x**2 - y**2)) == [{x: 0}, {x: -y}, {x: y}, {y: 0}] assert solve([x*y*(x**2 - y**2)]) == [{x: 0}, {x: -y}, {x: y}, {y: 0}] # issue 4739 assert solve(exp(log(5)*x) - 2**x, x) == [0] # issue 14791 assert solve(exp(log(5)*x) - exp(log(2)*x), x) == [0] f = Function('f') assert solve(y*f(log(5)*x) - y*f(log(2)*x), x) == [0] assert solve(f(x) - f(0), x) == [0] assert solve(f(x) - f(2 - x), x) == [1] raises(NotImplementedError, lambda: solve(f(x, y) - f(1, 2), x)) raises(NotImplementedError, lambda: solve(f(x, y) - f(2 - x, 2), x)) raises(ValueError, lambda: solve(f(x, y) - f(1 - x), x)) raises(ValueError, lambda: solve(f(x, y) - f(1), x))
# misc # make sure that the right variables is picked up in tsolve # shouldn't generate a GeneratorsNeeded error in _tsolve when the NaN is generated # for eq_down. Actual answers, as determined numerically are approx. +/- 0.83 raises(NotImplementedError, lambda: solve(sinh(x)*sinh(sinh(x)) + cosh(x)*cosh(sinh(x)) - 3))
# watch out for recursive loop in tsolve raises(NotImplementedError, lambda: solve((x + 2)**y*x - 3, x))
# issue 7245 assert solve(sin(sqrt(x))) == [0, pi**2]
# issue 7602 a, b = symbols('a, b', real=True, negative=False) assert str(solve(Eq(a, 0.5 - cos(pi*b)/2), b)) == \ '[2.0 - 0.318309886183791*acos(1.0 - 2.0*a), 0.318309886183791*acos(1.0 - 2.0*a)]'
# issue 15325 assert solve(y**(1/x) - z, x) == [log(y)/log(z)]
def test_solve_for_functions_derivatives(): t = Symbol('t') x = Function('x')(t) y = Function('y')(t) a11, a12, a21, a22, b1, b2 = symbols('a11,a12,a21,a22,b1,b2')
soln = solve([a11*x + a12*y - b1, a21*x + a22*y - b2], x, y) assert soln == { x: (a22*b1 - a12*b2)/(a11*a22 - a12*a21), y: (a11*b2 - a21*b1)/(a11*a22 - a12*a21), }
assert solve(x - 1, x) == [1] assert solve(3*x - 2, x) == [Rational(2, 3)]
soln = solve([a11*x.diff(t) + a12*y.diff(t) - b1, a21*x.diff(t) + a22*y.diff(t) - b2], x.diff(t), y.diff(t)) assert soln == { y.diff(t): (a11*b2 - a21*b1)/(a11*a22 - a12*a21), x.diff(t): (a22*b1 - a12*b2)/(a11*a22 - a12*a21) }
assert solve(x.diff(t) - 1, x.diff(t)) == [1] assert solve(3*x.diff(t) - 2, x.diff(t)) == [Rational(2, 3)]
eqns = {3*x - 1, 2*y - 4} assert solve(eqns, {x, y}) == { x: Rational(1, 3), y: 2 } x = Symbol('x') f = Function('f') F = x**2 + f(x)**2 - 4*x - 1 assert solve(F.diff(x), diff(f(x), x)) == [(-x + 2)/f(x)]
# Mixed cased with a Symbol and a Function x = Symbol('x') y = Function('y')(t)
soln = solve([a11*x + a12*y.diff(t) - b1, a21*x + a22*y.diff(t) - b2], x, y.diff(t)) assert soln == { y.diff(t): (a11*b2 - a21*b1)/(a11*a22 - a12*a21), x: (a22*b1 - a12*b2)/(a11*a22 - a12*a21) }
# issue 13263 x = Symbol('x') f = Function('f') soln = solve([f(x).diff(x) + f(x).diff(x, 2) - 1, f(x).diff(x) - f(x).diff(x, 2)], f(x).diff(x), f(x).diff(x, 2)) assert soln == { f(x).diff(x, 2): 1/2, f(x).diff(x): 1/2 }
soln = solve([f(x).diff(x, 2) + f(x).diff(x, 3) - 1, 1 - f(x).diff(x, 2) - f(x).diff(x, 3), 1 - f(x).diff(x,3)], f(x).diff(x, 2), f(x).diff(x, 3)) assert soln == { f(x).diff(x, 2): 0, f(x).diff(x, 3): 1 }
def test_issue_3725(): f = Function('f') F = x**2 + f(x)**2 - 4*x - 1 e = F.diff(x) assert solve(e, f(x).diff(x)) in [[(2 - x)/f(x)], [-((x - 2)/f(x))]]
def test_issue_3870(): a, b, c, d = symbols('a b c d') A = Matrix(2, 2, [a, b, c, d]) B = Matrix(2, 2, [0, 2, -3, 0]) C = Matrix(2, 2, [1, 2, 3, 4])
assert solve(A*B - C, [a, b, c, d]) == {a: 1, b: Rational(-1, 3), c: 2, d: -1} assert solve([A*B - C], [a, b, c, d]) == {a: 1, b: Rational(-1, 3), c: 2, d: -1} assert solve(Eq(A*B, C), [a, b, c, d]) == {a: 1, b: Rational(-1, 3), c: 2, d: -1}
assert solve([A*B - B*A], [a, b, c, d]) == {a: d, b: Rational(-2, 3)*c} assert solve([A*C - C*A], [a, b, c, d]) == {a: d - c, b: Rational(2, 3)*c} assert solve([A*B - B*A, A*C - C*A], [a, b, c, d]) == {a: d, b: 0, c: 0}
assert solve([Eq(A*B, B*A)], [a, b, c, d]) == {a: d, b: Rational(-2, 3)*c} assert solve([Eq(A*C, C*A)], [a, b, c, d]) == {a: d - c, b: Rational(2, 3)*c} assert solve([Eq(A*B, B*A), Eq(A*C, C*A)], [a, b, c, d]) == {a: d, b: 0, c: 0}
def test_solve_linear(): w = Wild('w') assert solve_linear(x, x) == (0, 1) assert solve_linear(x, exclude=[x]) == (0, 1) assert solve_linear(x, symbols=[w]) == (0, 1) assert solve_linear(x, y - 2*x) in [(x, y/3), (y, 3*x)] assert solve_linear(x, y - 2*x, exclude=[x]) == (y, 3*x) assert solve_linear(3*x - y, 0) in [(x, y/3), (y, 3*x)] assert solve_linear(3*x - y, 0, [x]) == (x, y/3) assert solve_linear(3*x - y, 0, [y]) == (y, 3*x) assert solve_linear(x**2/y, 1) == (y, x**2) assert solve_linear(w, x) in [(w, x), (x, w)] assert solve_linear(cos(x)**2 + sin(x)**2 + 2 + y) == \ (y, -2 - cos(x)**2 - sin(x)**2) assert solve_linear(cos(x)**2 + sin(x)**2 + 2 + y, symbols=[x]) == (0, 1) assert solve_linear(Eq(x, 3)) == (x, 3) assert solve_linear(1/(1/x - 2)) == (0, 0) assert solve_linear((x + 1)*exp(-x), symbols=[x]) == (x, -1) assert solve_linear((x + 1)*exp(x), symbols=[x]) == ((x + 1)*exp(x), 1) assert solve_linear(x*exp(-x**2), symbols=[x]) == (x, 0) assert solve_linear(0**x - 1) == (0**x - 1, 1) assert solve_linear(1 + 1/(x - 1)) == (x, 0) eq = y*cos(x)**2 + y*sin(x)**2 - y # = y*(1 - 1) = 0 assert solve_linear(eq) == (0, 1) eq = cos(x)**2 + sin(x)**2 # = 1 assert solve_linear(eq) == (0, 1) raises(ValueError, lambda: solve_linear(Eq(x, 3), 3))
def test_solve_undetermined_coeffs(): assert solve_undetermined_coeffs(a*x**2 + b*x**2 + b*x + 2*c*x + c + 1, [a, b, c], x) == \ {a: -2, b: 2, c: -1} # Test that rational functions work assert solve_undetermined_coeffs(a/x + b/(x + 1) - (2*x + 1)/(x**2 + x), [a, b], x) == \ {a: 1, b: 1} # Test cancellation in rational functions assert solve_undetermined_coeffs(((c + 1)*a*x**2 + (c + 1)*b*x**2 + (c + 1)*b*x + (c + 1)*2*c*x + (c + 1)**2)/(c + 1), [a, b, c], x) == \ {a: -2, b: 2, c: -1}
def test_solve_inequalities(): x = Symbol('x') sol = And(S.Zero < x, x < oo) assert solve(x + 1 > 1) == sol assert solve([x + 1 > 1]) == sol assert solve([x + 1 > 1], x) == sol assert solve([x + 1 > 1], [x]) == sol
system = [Lt(x**2 - 2, 0), Gt(x**2 - 1, 0)] assert solve(system) == \ And(Or(And(Lt(-sqrt(2), x), Lt(x, -1)), And(Lt(1, x), Lt(x, sqrt(2)))), Eq(0, 0))
x = Symbol('x', real=True) system = [Lt(x**2 - 2, 0), Gt(x**2 - 1, 0)] assert solve(system) == \ Or(And(Lt(-sqrt(2), x), Lt(x, -1)), And(Lt(1, x), Lt(x, sqrt(2))))
# issues 6627, 3448 assert solve((x - 3)/(x - 2) < 0, x) == And(Lt(2, x), Lt(x, 3)) assert solve(x/(x + 1) > 1, x) == And(Lt(-oo, x), Lt(x, -1))
assert solve(sin(x) > S.Half) == And(pi/6 < x, x < pi*Rational(5, 6))
assert solve(Eq(False, x < 1)) == (S.One <= x) & (x < oo) assert solve(Eq(True, x < 1)) == (-oo < x) & (x < 1) assert solve(Eq(x < 1, False)) == (S.One <= x) & (x < oo) assert solve(Eq(x < 1, True)) == (-oo < x) & (x < 1)
assert solve(Eq(False, x)) == False assert solve(Eq(0, x)) == [0] assert solve(Eq(True, x)) == True assert solve(Eq(1, x)) == [1] assert solve(Eq(False, ~x)) == True assert solve(Eq(True, ~x)) == False assert solve(Ne(True, x)) == False assert solve(Ne(1, x)) == (x > -oo) & (x < oo) & Ne(x, 1)
def test_issue_4793(): assert solve(1/x) == [] assert solve(x*(1 - 5/x)) == [5] assert solve(x + sqrt(x) - 2) == [1] assert solve(-(1 + x)/(2 + x)**2 + 1/(2 + x)) == [] assert solve(-x**2 - 2*x + (x + 1)**2 - 1) == [] assert solve((x/(x + 1) + 3)**(-2)) == [] assert solve(x/sqrt(x**2 + 1), x) == [0] assert solve(exp(x) - y, x) == [log(y)] assert solve(exp(x)) == [] assert solve(x**2 + x + sin(y)**2 + cos(y)**2 - 1, x) in [[0, -1], [-1, 0]] eq = 4*3**(5*x + 2) - 7 ans = solve(eq, x) assert len(ans) == 5 and all(eq.subs(x, a).n(chop=True) == 0 for a in ans) assert solve(log(x**2) - y**2/exp(x), x, y, set=True) == ( [x, y], {(x, sqrt(exp(x) * log(x ** 2))), (x, -sqrt(exp(x) * log(x ** 2)))}) assert solve(x**2*z**2 - z**2*y**2) == [{x: -y}, {x: y}, {z: 0}] assert solve((x - 1)/(1 + 1/(x - 1))) == [] assert solve(x**(y*z) - x, x) == [1] raises(NotImplementedError, lambda: solve(log(x) - exp(x), x)) raises(NotImplementedError, lambda: solve(2**x - exp(x) - 3))
def test_PR1964(): # issue 5171 assert solve(sqrt(x)) == solve(sqrt(x**3)) == [0] assert solve(sqrt(x - 1)) == [1] # issue 4462 a = Symbol('a') assert solve(-3*a/sqrt(x), x) == [] # issue 4486 assert solve(2*x/(x + 2) - 1, x) == [2] # issue 4496 assert set(solve((x**2/(7 - x)).diff(x))) == {S.Zero, S(14)} # issue 4695 f = Function('f') assert solve((3 - 5*x/f(x))*f(x), f(x)) == [x*Rational(5, 3)] # issue 4497 assert solve(1/root(5 + x, 5) - 9, x) == [Rational(-295244, 59049)]
assert solve(sqrt(x) + sqrt(sqrt(x)) - 4) == [(Rational(-1, 2) + sqrt(17)/2)**4] assert set(solve(Poly(sqrt(exp(x)) + sqrt(exp(-x)) - 4))) in \ [ {log((-sqrt(3) + 2)**2), log((sqrt(3) + 2)**2)}, {2*log(-sqrt(3) + 2), 2*log(sqrt(3) + 2)}, {log(-4*sqrt(3) + 7), log(4*sqrt(3) + 7)}, ] assert set(solve(Poly(exp(x) + exp(-x) - 4))) == \ {log(-sqrt(3) + 2), log(sqrt(3) + 2)} assert set(solve(x**y + x**(2*y) - 1, x)) == \ {(Rational(-1, 2) + sqrt(5)/2)**(1/y), (Rational(-1, 2) - sqrt(5)/2)**(1/y)}
assert solve(exp(x/y)*exp(-z/y) - 2, y) == [(x - z)/log(2)] assert solve( x**z*y**z - 2, z) in [[log(2)/(log(x) + log(y))], [log(2)/(log(x*y))]] # if you do inversion too soon then multiple roots (as for the following) # will be missed, e.g. if exp(3*x) = exp(3) -> 3*x = 3 E = S.Exp1 assert solve(exp(3*x) - exp(3), x) in [ [1, log(E*(Rational(-1, 2) - sqrt(3)*I/2)), log(E*(Rational(-1, 2) + sqrt(3)*I/2))], [1, log(-E/2 - sqrt(3)*E*I/2), log(-E/2 + sqrt(3)*E*I/2)], ]
# coverage test p = Symbol('p', positive=True) assert solve((1/p + 1)**(p + 1)) == []
def test_issue_5197(): x = Symbol('x', real=True) assert solve(x**2 + 1, x) == [] n = Symbol('n', integer=True, positive=True) assert solve((n - 1)*(n + 2)*(2*n - 1), n) == [1] x = Symbol('x', positive=True) y = Symbol('y') assert solve([x + 5*y - 2, -3*x + 6*y - 15], x, y) == [] # not {x: -3, y: 1} b/c x is positive # The solution following should not contain (-sqrt(2), sqrt(2)) assert solve((x + y)*n - y**2 + 2, x, y) == [(sqrt(2), -sqrt(2))] y = Symbol('y', positive=True) # The solution following should not contain {y: -x*exp(x/2)} assert solve(x**2 - y**2/exp(x), y, x, dict=True) == [{y: x*exp(x/2)}] x, y, z = symbols('x y z', positive=True) assert solve(z**2*x**2 - z**2*y**2/exp(x), y, x, z, dict=True) == [{y: x*exp(x/2)}]
def test_checking(): assert set( solve(x*(x - y/x), x, check=False)) == {sqrt(y), S.Zero, -sqrt(y)} assert set(solve(x*(x - y/x), x, check=True)) == {sqrt(y), -sqrt(y)} # {x: 0, y: 4} sets denominator to 0 in the following so system should return None assert solve((1/(1/x + 2), 1/(y - 3) - 1)) == [] # 0 sets denominator of 1/x to zero so None is returned assert solve(1/(1/x + 2)) == []
def test_issue_4671_4463_4467(): assert solve(sqrt(x**2 - 1) - 2) in ([sqrt(5), -sqrt(5)], [-sqrt(5), sqrt(5)]) assert solve((2**exp(y**2/x) + 2)/(x**2 + 15), y) == [ -sqrt(x*log(1 + I*pi/log(2))), sqrt(x*log(1 + I*pi/log(2)))]
C1, C2 = symbols('C1 C2') f = Function('f') assert solve(C1 + C2/x**2 - exp(-f(x)), f(x)) == [log(x**2/(C1*x**2 + C2))] a = Symbol('a') E = S.Exp1 assert solve(1 - log(a + 4*x**2), x) in ( [-sqrt(-a + E)/2, sqrt(-a + E)/2], [sqrt(-a + E)/2, -sqrt(-a + E)/2] ) assert solve(log(a**(-3) - x**2)/a, x) in ( [-sqrt(-1 + a**(-3)), sqrt(-1 + a**(-3))], [sqrt(-1 + a**(-3)), -sqrt(-1 + a**(-3))],) assert solve(1 - log(a + 4*x**2), x) in ( [-sqrt(-a + E)/2, sqrt(-a + E)/2], [sqrt(-a + E)/2, -sqrt(-a + E)/2],) assert solve((a**2 + 1)*(sin(a*x) + cos(a*x)), x) == [-pi/(4*a)] assert solve(3 - (sinh(a*x) + cosh(a*x)), x) == [log(3)/a] assert set(solve(3 - (sinh(a*x) + cosh(a*x)**2), x)) == \ {log(-2 + sqrt(5))/a, log(-sqrt(2) + 1)/a, log(-sqrt(5) - 2)/a, log(1 + sqrt(2))/a} assert solve(atan(x) - 1) == [tan(1)]
def test_issue_5132(): r, t = symbols('r,t') assert set(solve([r - x**2 - y**2, tan(t) - y/x], [x, y])) == \ {( -sqrt(r*cos(t)**2), -1*sqrt(r*cos(t)**2)*tan(t)), (sqrt(r*cos(t)**2), sqrt(r*cos(t)**2)*tan(t))} assert solve([exp(x) - sin(y), 1/y - 3], [x, y]) == \ [(log(sin(Rational(1, 3))), Rational(1, 3))] assert solve([exp(x) - sin(y), 1/exp(y) - 3], [x, y]) == \ [(log(-sin(log(3))), -log(3))] assert set(solve([exp(x) - sin(y), y**2 - 4], [x, y])) == \ {(log(-sin(2)), -S(2)), (log(sin(2)), S(2))} eqs = [exp(x)**2 - sin(y) + z**2, 1/exp(y) - 3] assert solve(eqs, set=True) == \ ([y, z], { (-log(3), sqrt(-exp(2*x) - sin(log(3)))), (-log(3), -sqrt(-exp(2*x) - sin(log(3))))}) assert solve(eqs, x, z, set=True) == ( [x, z], {(x, sqrt(-exp(2*x) + sin(y))), (x, -sqrt(-exp(2*x) + sin(y)))}) assert set(solve(eqs, x, y)) == \ { (log(-sqrt(-z**2 - sin(log(3)))), -log(3)), (log(-z**2 - sin(log(3)))/2, -log(3))} assert set(solve(eqs, y, z)) == \ { (-log(3), -sqrt(-exp(2*x) - sin(log(3)))), (-log(3), sqrt(-exp(2*x) - sin(log(3))))} eqs = [exp(x)**2 - sin(y) + z, 1/exp(y) - 3] assert solve(eqs, set=True) == ([y, z], { (-log(3), -exp(2*x) - sin(log(3)))}) assert solve(eqs, x, z, set=True) == ( [x, z], {(x, -exp(2*x) + sin(y))}) assert set(solve(eqs, x, y)) == { (log(-sqrt(-z - sin(log(3)))), -log(3)), (log(-z - sin(log(3)))/2, -log(3))} assert solve(eqs, z, y) == \ [(-exp(2*x) - sin(log(3)), -log(3))] assert solve((sqrt(x**2 + y**2) - sqrt(10), x + y - 4), set=True) == ( [x, y], {(S.One, S(3)), (S(3), S.One)}) assert set(solve((sqrt(x**2 + y**2) - sqrt(10), x + y - 4), x, y)) == \ {(S.One, S(3)), (S(3), S.One)}
def test_issue_5335(): lam, a0, conc = symbols('lam a0 conc') a = 0.005 b = 0.743436700916726 eqs = [lam + 2*y - a0*(1 - x/2)*x - a*x/2*x, a0*(1 - x/2)*x - 1*y - b*y, x + y - conc] sym = [x, y, a0] # there are 4 solutions obtained manually but only two are valid assert len(solve(eqs, sym, manual=True, minimal=True)) == 2 assert len(solve(eqs, sym)) == 2 # cf below with rational=False
@SKIP("Hangs")def _test_issue_5335_float(): # gives ZeroDivisionError: polynomial division lam, a0, conc = symbols('lam a0 conc') a = 0.005 b = 0.743436700916726 eqs = [lam + 2*y - a0*(1 - x/2)*x - a*x/2*x, a0*(1 - x/2)*x - 1*y - b*y, x + y - conc] sym = [x, y, a0] assert len(solve(eqs, sym, rational=False)) == 2
def test_issue_5767(): assert set(solve([x**2 + y + 4], [x])) == \ {(-sqrt(-y - 4),), (sqrt(-y - 4),)}
def test_polysys(): assert set(solve([x**2 + 2/y - 2, x + y - 3], [x, y])) == \ {(S.One, S(2)), (1 + sqrt(5), 2 - sqrt(5)), (1 - sqrt(5), 2 + sqrt(5))} assert solve([x**2 + y - 2, x**2 + y]) == [] # the ordering should be whatever the user requested assert solve([x**2 + y - 3, x - y - 4], (x, y)) != solve([x**2 + y - 3, x - y - 4], (y, x))
@slowdef test_unrad1(): raises(NotImplementedError, lambda: unrad(sqrt(x) + sqrt(x + 1) + sqrt(1 - sqrt(x)) + 3)) raises(NotImplementedError, lambda: unrad(sqrt(x) + (x + 1)**Rational(1, 3) + 2*sqrt(y)))
s = symbols('s', cls=Dummy)
# checkers to deal with possibility of answer coming # back with a sign change (cf issue 5203) def check(rv, ans): assert bool(rv[1]) == bool(ans[1]) if ans[1]: return s_check(rv, ans) e = rv[0].expand() a = ans[0].expand() return e in [a, -a] and rv[1] == ans[1]
def s_check(rv, ans): # get the dummy rv = list(rv) d = rv[0].atoms(Dummy) reps = list(zip(d, [s]*len(d))) # replace s with this dummy rv = (rv[0].subs(reps).expand(), [rv[1][0].subs(reps), rv[1][1].subs(reps)]) ans = (ans[0].subs(reps).expand(), [ans[1][0].subs(reps), ans[1][1].subs(reps)]) return str(rv[0]) in [str(ans[0]), str(-ans[0])] and \ str(rv[1]) == str(ans[1])
assert unrad(1) is None assert check(unrad(sqrt(x)), (x, [])) assert check(unrad(sqrt(x) + 1), (x - 1, [])) assert check(unrad(sqrt(x) + root(x, 3) + 2), (s**3 + s**2 + 2, [s, s**6 - x])) assert check(unrad(sqrt(x)*root(x, 3) + 2), (x**5 - 64, [])) assert check(unrad(sqrt(x) + (x + 1)**Rational(1, 3)), (x**3 - (x + 1)**2, [])) assert check(unrad(sqrt(x) + sqrt(x + 1) + sqrt(2*x)), (-2*sqrt(2)*x - 2*x + 1, [])) assert check(unrad(sqrt(x) + sqrt(x + 1) + 2), (16*x - 9, [])) assert check(unrad(sqrt(x) + sqrt(x + 1) + sqrt(1 - x)), (5*x**2 - 4*x, [])) assert check(unrad(a*sqrt(x) + b*sqrt(x) + c*sqrt(y) + d*sqrt(y)), ((a*sqrt(x) + b*sqrt(x))**2 - (c*sqrt(y) + d*sqrt(y))**2, [])) assert check(unrad(sqrt(x) + sqrt(1 - x)), (2*x - 1, [])) assert check(unrad(sqrt(x) + sqrt(1 - x) - 3), (x**2 - x + 16, [])) assert check(unrad(sqrt(x) + sqrt(1 - x) + sqrt(2 + x)), (5*x**2 - 2*x + 1, [])) assert unrad(sqrt(x) + sqrt(1 - x) + sqrt(2 + x) - 3) in [ (25*x**4 + 376*x**3 + 1256*x**2 - 2272*x + 784, []), (25*x**8 - 476*x**6 + 2534*x**4 - 1468*x**2 + 169, [])] assert unrad(sqrt(x) + sqrt(1 - x) + sqrt(2 + x) - sqrt(1 - 2*x)) == \ (41*x**4 + 40*x**3 + 232*x**2 - 160*x + 16, []) # orig root at 0.487 assert check(unrad(sqrt(x) + sqrt(x + 1)), (S.One, []))
eq = sqrt(x) + sqrt(x + 1) + sqrt(1 - sqrt(x)) assert check(unrad(eq), (16*x**2 - 9*x, [])) assert set(solve(eq, check=False)) == {S.Zero, Rational(9, 16)} assert solve(eq) == [] # but this one really does have those solutions assert set(solve(sqrt(x) - sqrt(x + 1) + sqrt(1 - sqrt(x)))) == \ {S.Zero, Rational(9, 16)}
assert check(unrad(sqrt(x) + root(x + 1, 3) + 2*sqrt(y), y), (S('2*sqrt(x)*(x + 1)**(1/3) + x - 4*y + (x + 1)**(2/3)'), [])) assert check(unrad(sqrt(x/(1 - x)) + (x + 1)**Rational(1, 3)), (x**5 - x**4 - x**3 + 2*x**2 + x - 1, [])) assert check(unrad(sqrt(x/(1 - x)) + 2*sqrt(y), y), (4*x*y + x - 4*y, [])) assert check(unrad(sqrt(x)*sqrt(1 - x) + 2, x), (x**2 - x + 4, []))
# http://tutorial.math.lamar.edu/ # Classes/Alg/SolveRadicalEqns.aspx#Solve_Rad_Ex2_a assert solve(Eq(x, sqrt(x + 6))) == [3] assert solve(Eq(x + sqrt(x - 4), 4)) == [4] assert solve(Eq(1, x + sqrt(2*x - 3))) == [] assert set(solve(Eq(sqrt(5*x + 6) - 2, x))) == {-S.One, S(2)} assert set(solve(Eq(sqrt(2*x - 1) - sqrt(x - 4), 2))) == {S(5), S(13)} assert solve(Eq(sqrt(x + 7) + 2, sqrt(3 - x))) == [-6] # http://www.purplemath.com/modules/solverad.htm assert solve((2*x - 5)**Rational(1, 3) - 3) == [16] assert set(solve(x + 1 - root(x**4 + 4*x**3 - x, 4))) == \ {Rational(-1, 2), Rational(-1, 3)} assert set(solve(sqrt(2*x**2 - 7) - (3 - x))) == {-S(8), S(2)} assert solve(sqrt(2*x + 9) - sqrt(x + 1) - sqrt(x + 4)) == [0] assert solve(sqrt(x + 4) + sqrt(2*x - 1) - 3*sqrt(x - 1)) == [5] assert solve(sqrt(x)*sqrt(x - 7) - 12) == [16] assert solve(sqrt(x - 3) + sqrt(x) - 3) == [4] assert solve(sqrt(9*x**2 + 4) - (3*x + 2)) == [0] assert solve(sqrt(x) - 2 - 5) == [49] assert solve(sqrt(x - 3) - sqrt(x) - 3) == [] assert solve(sqrt(x - 1) - x + 7) == [10] assert solve(sqrt(x - 2) - 5) == [27] assert solve(sqrt(17*x - sqrt(x**2 - 5)) - 7) == [3] assert solve(sqrt(x) - sqrt(x - 1) + sqrt(sqrt(x))) == []
# don't posify the expression in unrad and do use _mexpand z = sqrt(2*x + 1)/sqrt(x) - sqrt(2 + 1/x) p = posify(z)[0] assert solve(p) == [] assert solve(z) == [] assert solve(z + 6*I) == [Rational(-1, 11)] assert solve(p + 6*I) == [] # issue 8622 assert unrad(root(x + 1, 5) - root(x, 3)) == ( -(x**5 - x**3 - 3*x**2 - 3*x - 1), []) # issue #8679 assert check(unrad(x + root(x, 3) + root(x, 3)**2 + sqrt(y), x), (s**3 + s**2 + s + sqrt(y), [s, s**3 - x]))
# for coverage assert check(unrad(sqrt(x) + root(x, 3) + y), (s**3 + s**2 + y, [s, s**6 - x])) assert solve(sqrt(x) + root(x, 3) - 2) == [1] raises(NotImplementedError, lambda: solve(sqrt(x) + root(x, 3) + root(x + 1, 5) - 2)) # fails through a different code path raises(NotImplementedError, lambda: solve(-sqrt(2) + cosh(x)/x)) # unrad some assert solve(sqrt(x + root(x, 3))+root(x - y, 5), y) == [ x + (x**Rational(1, 3) + x)**Rational(5, 2)] assert check(unrad(sqrt(x) - root(x + 1, 3)*sqrt(x + 2) + 2), (s**10 + 8*s**8 + 24*s**6 - 12*s**5 - 22*s**4 - 160*s**3 - 212*s**2 - 192*s - 56, [s, s**2 - x])) e = root(x + 1, 3) + root(x, 3) assert unrad(e) == (2*x + 1, []) eq = (sqrt(x) + sqrt(x + 1) + sqrt(1 - x) - 6*sqrt(5)/5) assert check(unrad(eq), (15625*x**4 + 173000*x**3 + 355600*x**2 - 817920*x + 331776, [])) assert check(unrad(root(x, 4) + root(x, 4)**3 - 1), (s**3 + s - 1, [s, s**4 - x])) assert check(unrad(root(x, 2) + root(x, 2)**3 - 1), (x**3 + 2*x**2 + x - 1, [])) assert unrad(x**0.5) is None assert check(unrad(t + root(x + y, 5) + root(x + y, 5)**3), (s**3 + s + t, [s, s**5 - x - y])) assert check(unrad(x + root(x + y, 5) + root(x + y, 5)**3, y), (s**3 + s + x, [s, s**5 - x - y])) assert check(unrad(x + root(x + y, 5) + root(x + y, 5)**3, x), (s**5 + s**3 + s - y, [s, s**5 - x - y])) assert check(unrad(root(x - 1, 3) + root(x + 1, 5) + root(2, 5)), (s**5 + 5*2**Rational(1, 5)*s**4 + s**3 + 10*2**Rational(2, 5)*s**3 + 10*2**Rational(3, 5)*s**2 + 5*2**Rational(4, 5)*s + 4, [s, s**3 - x + 1])) raises(NotImplementedError, lambda: unrad((root(x, 2) + root(x, 3) + root(x, 4)).subs(x, x**5 - x + 1)))
# the simplify flag should be reset to False for unrad results; # if it's not then this next test will take a long time assert solve(root(x, 3) + root(x, 5) - 2) == [1] eq = (sqrt(x) + sqrt(x + 1) + sqrt(1 - x) - 6*sqrt(5)/5) assert check(unrad(eq), ((5*x - 4)*(3125*x**3 + 37100*x**2 + 100800*x - 82944), [])) ans = S('''
[4/5, -1484/375 + 172564/(140625*(114*sqrt(12657)/78125 + 12459439/52734375)**(1/3)) + 4*(114*sqrt(12657)/78125 + 12459439/52734375)**(1/3)]''')
assert solve(eq) == ans # duplicate radical handling assert check(unrad(sqrt(x + root(x + 1, 3)) - root(x + 1, 3) - 2), (s**3 - s**2 - 3*s - 5, [s, s**3 - x - 1])) # cov post-processing e = root(x**2 + 1, 3) - root(x**2 - 1, 5) - 2 assert check(unrad(e), (s**5 - 10*s**4 + 39*s**3 - 80*s**2 + 80*s - 30, [s, s**3 - x**2 - 1]))
e = sqrt(x + root(x + 1, 2)) - root(x + 1, 3) - 2 assert check(unrad(e), (s**6 - 2*s**5 - 7*s**4 - 3*s**3 + 26*s**2 + 40*s + 25, [s, s**3 - x - 1])) assert check(unrad(e, _reverse=True), (s**6 - 14*s**5 + 73*s**4 - 187*s**3 + 276*s**2 - 228*s + 89, [s, s**2 - x - sqrt(x + 1)])) # this one needs r0, r1 reversal to work assert check(unrad(sqrt(x + sqrt(root(x, 3) - 1)) - root(x, 6) - 2), (s**12 - 2*s**8 - 8*s**7 - 8*s**6 + s**4 + 8*s**3 + 23*s**2 + 32*s + 17, [s, s**6 - x]))
# why does this pass assert unrad(root(cosh(x), 3)/x*root(x + 1, 5) - 1) == ( -(x**15 - x**3*cosh(x)**5 - 3*x**2*cosh(x)**5 - 3*x*cosh(x)**5 - cosh(x)**5), []) # and this fail? #assert unrad(sqrt(cosh(x)/x) + root(x + 1, 3)*sqrt(x) - 1) == ( # -s**6 + 6*s**5 - 15*s**4 + 20*s**3 - 15*s**2 + 6*s + x**5 + # 2*x**4 + x**3 - 1, [s, s**2 - cosh(x)/x])
# watch for symbols in exponents assert unrad(S('(x+y)**(2*y/3) + (x+y)**(1/3) + 1')) is None assert check(unrad(S('(x+y)**(2*y/3) + (x+y)**(1/3) + 1'), x), (s**(2*y) + s + 1, [s, s**3 - x - y])) # should _Q be so lenient? assert unrad(x**(S.Half/y) + y, x) == (x**(1/y) - y**2, [])
# This tests two things: that if full unrad is attempted and fails # the solution should still be found; also it tests that the use of # composite assert len(solve(sqrt(y)*x + x**3 - 1, x)) == 3 assert len(solve(-512*y**3 + 1344*(x + 2)**Rational(1, 3)*y**2 - 1176*(x + 2)**Rational(2, 3)*y - 169*x + 686, y, _unrad=False)) == 3
# watch out for when the cov doesn't involve the symbol of interest eq = S('-x + (7*y/8 - (27*x/2 + 27*sqrt(x**2)/2)**(1/3)/3)**3 - 1') assert solve(eq, y) == [ 2**(S(2)/3)*(27*x + 27*sqrt(x**2))**(S(1)/3)*S(4)/21 + (512*x/343 + S(512)/343)**(S(1)/3)*(-S(1)/2 - sqrt(3)*I/2), 2**(S(2)/3)*(27*x + 27*sqrt(x**2))**(S(1)/3)*S(4)/21 + (512*x/343 + S(512)/343)**(S(1)/3)*(-S(1)/2 + sqrt(3)*I/2), 2**(S(2)/3)*(27*x + 27*sqrt(x**2))**(S(1)/3)*S(4)/21 + (512*x/343 + S(512)/343)**(S(1)/3)]
eq = root(x + 1, 3) - (root(x, 3) + root(x, 5)) assert check(unrad(eq), (3*s**13 + 3*s**11 + s**9 - 1, [s, s**15 - x])) assert check(unrad(eq - 2), (3*s**13 + 3*s**11 + 6*s**10 + s**9 + 12*s**8 + 6*s**6 + 12*s**5 + 12*s**3 + 7, [s, s**15 - x])) assert check(unrad(root(x, 3) - root(x + 1, 4)/2 + root(x + 2, 3)), (s*(4096*s**9 + 960*s**8 + 48*s**7 - s**6 - 1728), [s, s**4 - x - 1])) # orig expr has two real roots: -1, -.389 assert check(unrad(root(x, 3) + root(x + 1, 4) - root(x + 2, 3)/2), (343*s**13 + 2904*s**12 + 1344*s**11 + 512*s**10 - 1323*s**9 - 3024*s**8 - 1728*s**7 + 1701*s**5 + 216*s**4 - 729*s, [s, s**4 - x - 1])) # orig expr has one real root: -0.048 assert check(unrad(root(x, 3)/2 - root(x + 1, 4) + root(x + 2, 3)), (729*s**13 - 216*s**12 + 1728*s**11 - 512*s**10 + 1701*s**9 - 3024*s**8 + 1344*s**7 + 1323*s**5 - 2904*s**4 + 343*s, [s, s**4 - x - 1])) # orig expr has 2 real roots: -0.91, -0.15 assert check(unrad(root(x, 3)/2 - root(x + 1, 4) + root(x + 2, 3) - 2), (729*s**13 + 1242*s**12 + 18496*s**10 + 129701*s**9 + 388602*s**8 + 453312*s**7 - 612864*s**6 - 3337173*s**5 - 6332418*s**4 - 7134912*s**3 - 5064768*s**2 - 2111913*s - 398034, [s, s**4 - x - 1])) # orig expr has 1 real root: 19.53
ans = solve(sqrt(x) + sqrt(x + 1) - sqrt(1 - x) - sqrt(2 + x)) assert len(ans) == 1 and NS(ans[0])[:4] == '0.73' # the fence optimization problem # https://github.com/sympy/sympy/issues/4793#issuecomment-36994519 F = Symbol('F') eq = F - (2*x + 2*y + sqrt(x**2 + y**2)) ans = F*Rational(2, 7) - sqrt(2)*F/14 X = solve(eq, x, check=False) for xi in reversed(X): # reverse since currently, ans is the 2nd one Y = solve((x*y).subs(x, xi).diff(y), y, simplify=False, check=False) if any((a - ans).expand().is_zero for a in Y): break else: assert None # no answer was found assert solve(sqrt(x + 1) + root(x, 3) - 2) == S('''
[(-11/(9*(47/54 + sqrt(93)/6)**(1/3)) + 1/3 + (47/54 + sqrt(93)/6)**(1/3))**3]''')
assert solve(sqrt(sqrt(x + 1)) + x**Rational(1, 3) - 2) == S('''
[(-sqrt(-2*(-1/16 + sqrt(6913)/16)**(1/3) + 6/(-1/16 + sqrt(6913)/16)**(1/3) + 17/2 + 121/(4*sqrt(-6/(-1/16 + sqrt(6913)/16)**(1/3) + 2*(-1/16 + sqrt(6913)/16)**(1/3) + 17/4)))/2 + sqrt(-6/(-1/16 + sqrt(6913)/16)**(1/3) + 2*(-1/16 + sqrt(6913)/16)**(1/3) + 17/4)/2 + 9/4)**3]''')
assert solve(sqrt(x) + root(sqrt(x) + 1, 3) - 2) == S('''
[(-(81/2 + 3*sqrt(741)/2)**(1/3)/3 + (81/2 + 3*sqrt(741)/2)**(-1/3) + 2)**2]''')
eq = S('''
-x + (1/2 - sqrt(3)*I/2)*(3*x**3/2 - x*(3*x**2 - 34)/2 + sqrt((-3*x**3 + x*(3*x**2 - 34) + 90)**2/4 - 39304/27) - 45)**(1/3) + 34/(3*(1/2 - sqrt(3)*I/2)*(3*x**3/2 - x*(3*x**2 - 34)/2 + sqrt((-3*x**3 + x*(3*x**2 - 34) + 90)**2/4 - 39304/27) - 45)**(1/3))''')
assert check(unrad(eq), (s*-(-s**6 + sqrt(3)*s**6*I - 153*2**Rational(2, 3)*3**Rational(1, 3)*s**4 + 51*12**Rational(1, 3)*s**4 - 102*2**Rational(2, 3)*3**Rational(5, 6)*s**4*I - 1620*s**3 + 1620*sqrt(3)*s**3*I + 13872*18**Rational(1, 3)*s**2 - 471648 + 471648*sqrt(3)*I), [s, s**3 - 306*x - sqrt(3)*sqrt(31212*x**2 - 165240*x + 61484) + 810]))
assert solve(eq) == [] # not other code errors eq = root(x, 3) - root(y, 3) + root(x, 5) assert check(unrad(eq), (s**15 + 3*s**13 + 3*s**11 + s**9 - y, [s, s**15 - x])) eq = root(x, 3) + root(y, 3) + root(x*y, 4) assert check(unrad(eq), (s*y*(-s**12 - 3*s**11*y - 3*s**10*y**2 - s**9*y**3 - 3*s**8*y**2 + 21*s**7*y**3 - 3*s**6*y**4 - 3*s**4*y**4 - 3*s**3*y**5 - y**6), [s, s**4 - x*y])) raises(NotImplementedError, lambda: unrad(root(x, 3) + root(y, 3) + root(x*y, 5)))
# Test unrad with an Equality eq = Eq(-x**(S(1)/5) + x**(S(1)/3), -3**(S(1)/3) - (-1)**(S(3)/5)*3**(S(1)/5)) assert check(unrad(eq), (-s**5 + s**3 - 3**(S(1)/3) - (-1)**(S(3)/5)*3**(S(1)/5), [s, s**15 - x]))
# make sure buried radicals are exposed s = sqrt(x) - 1 assert unrad(s**2 - s**3) == (x**3 - 6*x**2 + 9*x - 4, []) # make sure numerators which are already polynomial are rejected assert unrad((x/(x + 1) + 3)**(-2), x) is None
@slowdef test_unrad_slow(): # this has roots with multiplicity > 1; there should be no # repeats in roots obtained, however eq = (sqrt(1 + sqrt(1 - 4*x**2)) - x*(1 + sqrt(1 + 2*sqrt(1 - 4*x**2)))) assert solve(eq) == [S.Half]
@XFAILdef test_unrad_fail(): # this only works if we check real_root(eq.subs(x, Rational(1, 3))) # but checksol doesn't work like that assert solve(root(x**3 - 3*x**2, 3) + 1 - x) == [Rational(1, 3)] assert solve(root(x + 1, 3) + root(x**2 - 2, 5) + 1) == [ -1, -1 + CRootOf(x**5 + x**4 + 5*x**3 + 8*x**2 + 10*x + 5, 0)**3]
def test_checksol(): x, y, r, t = symbols('x, y, r, t') eq = r - x**2 - y**2 dict_var_soln = {y: - sqrt(r) / sqrt(tan(t)**2 + 1), x: -sqrt(r)*tan(t)/sqrt(tan(t)**2 + 1)} assert checksol(eq, dict_var_soln) == True assert checksol(Eq(x, False), {x: False}) is True assert checksol(Ne(x, False), {x: False}) is False assert checksol(Eq(x < 1, True), {x: 0}) is True assert checksol(Eq(x < 1, True), {x: 1}) is False assert checksol(Eq(x < 1, False), {x: 1}) is True assert checksol(Eq(x < 1, False), {x: 0}) is False assert checksol(Eq(x + 1, x**2 + 1), {x: 1}) is True assert checksol([x - 1, x**2 - 1], x, 1) is True assert checksol([x - 1, x**2 - 2], x, 1) is False assert checksol(Poly(x**2 - 1), x, 1) is True raises(ValueError, lambda: checksol(x, 1)) raises(ValueError, lambda: checksol([], x, 1))
def test__invert(): assert _invert(x - 2) == (2, x) assert _invert(2) == (2, 0) assert _invert(exp(1/x) - 3, x) == (1/log(3), x) assert _invert(exp(1/x + a/x) - 3, x) == ((a + 1)/log(3), x) assert _invert(a, x) == (a, 0)
def test_issue_4463(): assert solve(-a*x + 2*x*log(x), x) == [exp(a/2)] assert solve(x**x) == [] assert solve(x**x - 2) == [exp(LambertW(log(2)))] assert solve(((x - 3)*(x - 2))**((x - 3)*(x - 4))) == [2]
@slowdef test_issue_5114_solvers(): a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r = symbols('a:r')
# there is no 'a' in the equation set but this is how the # problem was originally posed syms = a, b, c, f, h, k, n eqs = [b + r/d - c/d, c*(1/d + 1/e + 1/g) - f/g - r/d, f*(1/g + 1/i + 1/j) - c/g - h/i, h*(1/i + 1/l + 1/m) - f/i - k/m, k*(1/m + 1/o + 1/p) - h/m - n/p, n*(1/p + 1/q) - k/p] assert len(solve(eqs, syms, manual=True, check=False, simplify=False)) == 1
def test_issue_5849(): # # XXX: This system does not have a solution for most values of the # parameters. Generally solve returns the empty set for systems that are # generically inconsistent. # I1, I2, I3, I4, I5, I6 = symbols('I1:7') dI1, dI4, dQ2, dQ4, Q2, Q4 = symbols('dI1,dI4,dQ2,dQ4,Q2,Q4')
e = ( I1 - I2 - I3, I3 - I4 - I5, I4 + I5 - I6, -I1 + I2 + I6, -2*I1 - 2*I3 - 2*I5 - 3*I6 - dI1/2 + 12, -I4 + dQ4, -I2 + dQ2, 2*I3 + 2*I5 + 3*I6 - Q2, I4 - 2*I5 + 2*Q4 + dI4 )
ans = [{ I1: I2 + I3, dI1: -4*I2 - 8*I3 - 4*I5 - 6*I6 + 24, I4: I3 - I5, dQ4: I3 - I5, Q4: -I3/2 + 3*I5/2 - dI4/2, dQ2: I2, Q2: 2*I3 + 2*I5 + 3*I6}]
v = I1, I4, Q2, Q4, dI1, dI4, dQ2, dQ4 assert solve(e, *v, manual=True, check=False, dict=True) == ans assert solve(e, *v, manual=True, check=False) == ans[0] assert solve(e, *v, manual=True) == [] assert solve(e, *v) == []
# the matrix solver (tested below) doesn't like this because it produces # a zero row in the matrix. Is this related to issue 4551? assert [ei.subs( ans[0]) for ei in e] == [0, 0, I3 - I6, -I3 + I6, 0, 0, 0, 0, 0]
def test_issue_5849_matrix(): '''Same as test_issue_5849 but solved with the matrix solver.
A solution only exists if I3 == I6 which is not generically true, but `solve` does not return conditions under which the solution is valid, only a solution that is canonical and consistent with the input. '''
# a simple example with the same issue # assert solve([x+y+z, x+y], [x, y]) == {x: y} # the longer example I1, I2, I3, I4, I5, I6 = symbols('I1:7') dI1, dI4, dQ2, dQ4, Q2, Q4 = symbols('dI1,dI4,dQ2,dQ4,Q2,Q4')
e = ( I1 - I2 - I3, I3 - I4 - I5, I4 + I5 - I6, -I1 + I2 + I6, -2*I1 - 2*I3 - 2*I5 - 3*I6 - dI1/2 + 12, -I4 + dQ4, -I2 + dQ2, 2*I3 + 2*I5 + 3*I6 - Q2, I4 - 2*I5 + 2*Q4 + dI4 ) assert solve(e, I1, I4, Q2, Q4, dI1, dI4, dQ2, dQ4) == []
def test_issue_21882():
a, b, c, d, f, g, k = unknowns = symbols('a, b, c, d, f, g, k')
equations = [ -k*a + b + 5*f/6 + 2*c/9 + 5*d/6 + 4*a/3, -k*f + 4*f/3 + d/2, -k*d + f/6 + d, 13*b/18 + 13*c/18 + 13*a/18, -k*c + b/2 + 20*c/9 + a, -k*b + b + c/18 + a/6, 5*b/3 + c/3 + a, 2*b/3 + 2*c + 4*a/3, -g, ]
answer = [ {a: 0, f: 0, b: 0, d: 0, c: 0, g: 0}, {a: 0, f: -d, b: 0, k: S(5)/6, c: 0, g: 0}, {a: -2*c, f: 0, b: c, d: 0, k: S(13)/18, g: 0}, ]
assert solve(equations, unknowns, dict=True) == answer
def test_issue_5901(): f, g, h = map(Function, 'fgh') a = Symbol('a') D = Derivative(f(x), x) G = Derivative(g(a), a) assert solve(f(x) + f(x).diff(x), f(x)) == \ [-D] assert solve(f(x) - 3, f(x)) == \ [3] assert solve(f(x) - 3*f(x).diff(x), f(x)) == \ [3*D] assert solve([f(x) - 3*f(x).diff(x)], f(x)) == \ {f(x): 3*D} assert solve([f(x) - 3*f(x).diff(x), f(x)**2 - y + 4], f(x), y) == \ [{f(x): 3*D, y: 9*D**2 + 4}] assert solve(-f(a)**2*g(a)**2 + f(a)**2*h(a)**2 + g(a).diff(a), h(a), g(a), set=True) == \ ([g(a)], { (-sqrt(h(a)**2*f(a)**2 + G)/f(a),), (sqrt(h(a)**2*f(a)**2+ G)/f(a),)}) args = [f(x).diff(x, 2)*(f(x) + g(x)) - g(x)**2 + 2, f(x), g(x)] assert set(solve(*args)) == \ {(-sqrt(2), sqrt(2)), (sqrt(2), -sqrt(2))} eqs = [f(x)**2 + g(x) - 2*f(x).diff(x), g(x)**2 - 4] assert solve(eqs, f(x), g(x), set=True) == \ ([f(x), g(x)], { (-sqrt(2*D - 2), S(2)), (sqrt(2*D - 2), S(2)), (-sqrt(2*D + 2), -S(2)), (sqrt(2*D + 2), -S(2))})
# the underlying problem was in solve_linear that was not masking off # anything but a Mul or Add; it now raises an error if it gets anything # but a symbol and solve handles the substitutions necessary so solve_linear # won't make this error raises( ValueError, lambda: solve_linear(f(x) + f(x).diff(x), symbols=[f(x)])) assert solve_linear(f(x) + f(x).diff(x), symbols=[x]) == \ (f(x) + Derivative(f(x), x), 1) assert solve_linear(f(x) + Integral(x, (x, y)), symbols=[x]) == \ (f(x) + Integral(x, (x, y)), 1) assert solve_linear(f(x) + Integral(x, (x, y)) + x, symbols=[x]) == \ (x + f(x) + Integral(x, (x, y)), 1) assert solve_linear(f(y) + Integral(x, (x, y)) + x, symbols=[x]) == \ (x, -f(y) - Integral(x, (x, y))) assert solve_linear(x - f(x)/a + (f(x) - 1)/a, symbols=[x]) == \ (x, 1/a) assert solve_linear(x + Derivative(2*x, x)) == \ (x, -2) assert solve_linear(x + Integral(x, y), symbols=[x]) == \ (x, 0) assert solve_linear(x + Integral(x, y) - 2, symbols=[x]) == \ (x, 2/(y + 1))
assert set(solve(x + exp(x)**2, exp(x))) == \ {-sqrt(-x), sqrt(-x)} assert solve(x + exp(x), x, implicit=True) == \ [-exp(x)] assert solve(cos(x) - sin(x), x, implicit=True) == [] assert solve(x - sin(x), x, implicit=True) == \ [sin(x)] assert solve(x**2 + x - 3, x, implicit=True) == \ [-x**2 + 3] assert solve(x**2 + x - 3, x**2, implicit=True) == \ [-x + 3]
def test_issue_5912(): assert set(solve(x**2 - x - 0.1, rational=True)) == \ {S.Half + sqrt(35)/10, -sqrt(35)/10 + S.Half} ans = solve(x**2 - x - 0.1, rational=False) assert len(ans) == 2 and all(a.is_Number for a in ans) ans = solve(x**2 - x - 0.1) assert len(ans) == 2 and all(a.is_Number for a in ans)
def test_float_handling(): def test(e1, e2): return len(e1.atoms(Float)) == len(e2.atoms(Float)) assert solve(x - 0.5, rational=True)[0].is_Rational assert solve(x - 0.5, rational=False)[0].is_Float assert solve(x - S.Half, rational=False)[0].is_Rational assert solve(x - 0.5, rational=None)[0].is_Float assert solve(x - S.Half, rational=None)[0].is_Rational assert test(nfloat(1 + 2*x), 1.0 + 2.0*x) for contain in [list, tuple, set]: ans = nfloat(contain([1 + 2*x])) assert type(ans) is contain and test(list(ans)[0], 1.0 + 2.0*x) k, v = list(nfloat({2*x: [1 + 2*x]}).items())[0] assert test(k, 2*x) and test(v[0], 1.0 + 2.0*x) assert test(nfloat(cos(2*x)), cos(2.0*x)) assert test(nfloat(3*x**2), 3.0*x**2) assert test(nfloat(3*x**2, exponent=True), 3.0*x**2.0) assert test(nfloat(exp(2*x)), exp(2.0*x)) assert test(nfloat(x/3), x/3.0) assert test(nfloat(x**4 + 2*x + cos(Rational(1, 3)) + 1), x**4 + 2.0*x + 1.94495694631474) # don't call nfloat if there is no solution tot = 100 + c + z + t assert solve(((.7 + c)/tot - .6, (.2 + z)/tot - .3, t/tot - .1)) == []
def test_check_assumptions(): x = symbols('x', positive=True) assert solve(x**2 - 1) == [1]
def test_issue_6056(): assert solve(tanh(x + 3)*tanh(x - 3) - 1) == [] assert solve(tanh(x - 1)*tanh(x + 1) + 1) == \ [I*pi*Rational(-3, 4), -I*pi/4, I*pi/4, I*pi*Rational(3, 4)] assert solve((tanh(x + 3)*tanh(x - 3) + 1)**2) == \ [I*pi*Rational(-3, 4), -I*pi/4, I*pi/4, I*pi*Rational(3, 4)]
def test_issue_5673(): eq = -x + exp(exp(LambertW(log(x)))*LambertW(log(x))) assert checksol(eq, x, 2) is True assert checksol(eq, x, 2, numerical=False) is None
def test_exclude(): R, C, Ri, Vout, V1, Vminus, Vplus, s = \ symbols('R, C, Ri, Vout, V1, Vminus, Vplus, s') Rf = symbols('Rf', positive=True) # to eliminate Rf = 0 soln eqs = [C*V1*s + Vplus*(-2*C*s - 1/R), Vminus*(-1/Ri - 1/Rf) + Vout/Rf, C*Vplus*s + V1*(-C*s - 1/R) + Vout/R, -Vminus + Vplus] assert solve(eqs, exclude=s*C*R) == [ { Rf: Ri*(C*R*s + 1)**2/(C*R*s), Vminus: Vplus, V1: 2*Vplus + Vplus/(C*R*s), Vout: C*R*Vplus*s + 3*Vplus + Vplus/(C*R*s)}, { Vplus: 0, Vminus: 0, V1: 0, Vout: 0}, ]
# TODO: Investigate why currently solution [0] is preferred over [1]. assert solve(eqs, exclude=[Vplus, s, C]) in [[{ Vminus: Vplus, V1: Vout/2 + Vplus/2 + sqrt((Vout - 5*Vplus)*(Vout - Vplus))/2, R: (Vout - 3*Vplus - sqrt(Vout**2 - 6*Vout*Vplus + 5*Vplus**2))/(2*C*Vplus*s), Rf: Ri*(Vout - Vplus)/Vplus, }, { Vminus: Vplus, V1: Vout/2 + Vplus/2 - sqrt((Vout - 5*Vplus)*(Vout - Vplus))/2, R: (Vout - 3*Vplus + sqrt(Vout**2 - 6*Vout*Vplus + 5*Vplus**2))/(2*C*Vplus*s), Rf: Ri*(Vout - Vplus)/Vplus, }], [{ Vminus: Vplus, Vout: (V1**2 - V1*Vplus - Vplus**2)/(V1 - 2*Vplus), Rf: Ri*(V1 - Vplus)**2/(Vplus*(V1 - 2*Vplus)), R: Vplus/(C*s*(V1 - 2*Vplus)), }]]
def test_high_order_roots(): s = x**5 + 4*x**3 + 3*x**2 + Rational(7, 4) assert set(solve(s)) == set(Poly(s*4, domain='ZZ').all_roots())
def test_minsolve_linear_system(): def count(dic): return len([x for x in dic.values() if x == 0]) assert count(solve([x + y + z, y + z + a + t], particular=True, quick=True)) \ == 3 assert count(solve([x + y + z, y + z + a + t], particular=True, quick=False)) \ == 3 assert count(solve([x + y + z, y + z + a], particular=True, quick=True)) == 1 assert count(solve([x + y + z, y + z + a], particular=True, quick=False)) == 2
def test_real_roots(): # cf. issue 6650 x = Symbol('x', real=True) assert len(solve(x**5 + x**3 + 1)) == 1
def test_issue_6528(): eqs = [ 327600995*x**2 - 37869137*x + 1809975124*y**2 - 9998905626, 895613949*x**2 - 273830224*x*y + 530506983*y**2 - 10000000000] # two expressions encountered are > 1400 ops long so if this hangs # it is likely because simplification is being done assert len(solve(eqs, y, x, check=False)) == 4
def test_overdetermined(): x = symbols('x', real=True) eqs = [Abs(4*x - 7) - 5, Abs(3 - 8*x) - 1] assert solve(eqs, x) == [(S.Half,)] assert solve(eqs, x, manual=True) == [(S.Half,)] assert solve(eqs, x, manual=True, check=False) == [(S.Half,), (S(3),)]
def test_issue_6605(): x = symbols('x') assert solve(4**(x/2) - 2**(x/3)) == [0, 3*I*pi/log(2)] # while the first one passed, this one failed x = symbols('x', real=True) assert solve(5**(x/2) - 2**(x/3)) == [0] b = sqrt(6)*sqrt(log(2))/sqrt(log(5)) assert solve(5**(x/2) - 2**(3/x)) == [-b, b]
def test__ispow(): assert _ispow(x**2) assert not _ispow(x) assert not _ispow(True)
def test_issue_6644(): eq = -sqrt((m - q)**2 + (-m/(2*q) + S.Half)**2) + sqrt((-m**2/2 - sqrt( 4*m**4 - 4*m**2 + 8*m + 1)/4 - Rational(1, 4))**2 + (m**2/2 - m - sqrt( 4*m**4 - 4*m**2 + 8*m + 1)/4 - Rational(1, 4))**2) sol = solve(eq, q, simplify=False, check=False) assert len(sol) == 5
def test_issue_6752(): assert solve([a**2 + a, a - b], [a, b]) == [(-1, -1), (0, 0)] assert solve([a**2 + a*c, a - b], [a, b]) == [(0, 0), (-c, -c)]
def test_issue_6792(): assert solve(x*(x - 1)**2*(x + 1)*(x**6 - x + 1)) == [ -1, 0, 1, CRootOf(x**6 - x + 1, 0), CRootOf(x**6 - x + 1, 1), CRootOf(x**6 - x + 1, 2), CRootOf(x**6 - x + 1, 3), CRootOf(x**6 - x + 1, 4), CRootOf(x**6 - x + 1, 5)]
def test_issues_6819_6820_6821_6248_8692(): # issue 6821 x, y = symbols('x y', real=True) assert solve(abs(x + 3) - 2*abs(x - 3)) == [1, 9] assert solve([abs(x) - 2, arg(x) - pi], x) == [(-2,)] assert set(solve(abs(x - 7) - 8)) == {-S.One, S(15)}
# issue 8692 assert solve(Eq(Abs(x + 1) + Abs(x**2 - 7), 9), x) == [ Rational(-1, 2) + sqrt(61)/2, -sqrt(69)/2 + S.Half]
# issue 7145 assert solve(2*abs(x) - abs(x - 1)) == [-1, Rational(1, 3)]
x = symbols('x') assert solve([re(x) - 1, im(x) - 2], x) == [ {re(x): 1, x: 1 + 2*I, im(x): 2}]
# check for 'dict' handling of solution eq = sqrt(re(x)**2 + im(x)**2) - 3 assert solve(eq) == solve(eq, x)
i = symbols('i', imaginary=True) assert solve(abs(i) - 3) == [-3*I, 3*I] raises(NotImplementedError, lambda: solve(abs(x) - 3))
w = symbols('w', integer=True) assert solve(2*x**w - 4*y**w, w) == solve((x/y)**w - 2, w)
x, y = symbols('x y', real=True) assert solve(x + y*I + 3) == {y: 0, x: -3} # issue 2642 assert solve(x*(1 + I)) == [0]
x, y = symbols('x y', imaginary=True) assert solve(x + y*I + 3 + 2*I) == {x: -2*I, y: 3*I}
x = symbols('x', real=True) assert solve(x + y + 3 + 2*I) == {x: -3, y: -2*I}
# issue 6248 f = Function('f') assert solve(f(x + 1) - f(2*x - 1)) == [2] assert solve(log(x + 1) - log(2*x - 1)) == [2]
x = symbols('x') assert solve(2**x + 4**x) == [I*pi/log(2)]
def test_issue_14607(): # issue 14607 s, tau_c, tau_1, tau_2, phi, K = symbols( 's, tau_c, tau_1, tau_2, phi, K')
target = (s**2*tau_1*tau_2 + s*tau_1 + s*tau_2 + 1)/(K*s*(-phi + tau_c))
K_C, tau_I, tau_D = symbols('K_C, tau_I, tau_D', positive=True, nonzero=True) PID = K_C*(1 + 1/(tau_I*s) + tau_D*s)
eq = (target - PID).together() eq *= denom(eq).simplify() eq = Poly(eq, s) c = eq.coeffs()
vars = [K_C, tau_I, tau_D] s = solve(c, vars, dict=True)
assert len(s) == 1
knownsolution = {K_C: -(tau_1 + tau_2)/(K*(phi - tau_c)), tau_I: tau_1 + tau_2, tau_D: tau_1*tau_2/(tau_1 + tau_2)}
for var in vars: assert s[0][var].simplify() == knownsolution[var].simplify()
def test_lambert_multivariate(): from sympy.abc import x, y assert _filtered_gens(Poly(x + 1/x + exp(x) + y), x) == {x, exp(x)} assert _lambert(x, x) == [] assert solve((x**2 - 2*x + 1).subs(x, log(x) + 3*x)) == [LambertW(3*S.Exp1)/3] assert solve((x**2 - 2*x + 1).subs(x, (log(x) + 3*x)**2 - 1)) == \ [LambertW(3*exp(-sqrt(2)))/3, LambertW(3*exp(sqrt(2)))/3] assert solve((x**2 - 2*x - 2).subs(x, log(x) + 3*x)) == \ [LambertW(3*exp(1 - sqrt(3)))/3, LambertW(3*exp(1 + sqrt(3)))/3] eq = (x*exp(x) - 3).subs(x, x*exp(x)) assert solve(eq) == [LambertW(3*exp(-LambertW(3)))] # coverage test raises(NotImplementedError, lambda: solve(x - sin(x)*log(y - x), x)) ans = [3, -3*LambertW(-log(3)/3)/log(3)] # 3 and 2.478... assert solve(x**3 - 3**x, x) == ans assert set(solve(3*log(x) - x*log(3))) == set(ans) assert solve(LambertW(2*x) - y, x) == [y*exp(y)/2]
@XFAILdef test_other_lambert(): assert solve(3*sin(x) - x*sin(3), x) == [3] assert set(solve(x**a - a**x), x) == { a, -a*LambertW(-log(a)/a)/log(a)}
@slowdef test_lambert_bivariate(): # tests passing current implementation assert solve((x**2 + x)*exp(x**2 + x) - 1) == [ Rational(-1, 2) + sqrt(1 + 4*LambertW(1))/2, Rational(-1, 2) - sqrt(1 + 4*LambertW(1))/2] assert solve((x**2 + x)*exp((x**2 + x)*2) - 1) == [ Rational(-1, 2) + sqrt(1 + 2*LambertW(2))/2, Rational(-1, 2) - sqrt(1 + 2*LambertW(2))/2] assert solve(a/x + exp(x/2), x) == [2*LambertW(-a/2)] assert solve((a/x + exp(x/2)).diff(x), x) == \ [4*LambertW(-sqrt(2)*sqrt(a)/4), 4*LambertW(sqrt(2)*sqrt(a)/4)] assert solve((1/x + exp(x/2)).diff(x), x) == \ [4*LambertW(-sqrt(2)/4), 4*LambertW(sqrt(2)/4), # nsimplifies as 2*2**(141/299)*3**(206/299)*5**(205/299)*7**(37/299)/21 4*LambertW(-sqrt(2)/4, -1)] assert solve(x*log(x) + 3*x + 1, x) == \ [exp(-3 + LambertW(-exp(3)))] assert solve(-x**2 + 2**x, x) == [2, 4, -2*LambertW(log(2)/2)/log(2)] assert solve(x**2 - 2**x, x) == [2, 4, -2*LambertW(log(2)/2)/log(2)] ans = solve(3*x + 5 + 2**(-5*x + 3), x) assert len(ans) == 1 and ans[0].expand() == \ Rational(-5, 3) + LambertW(-10240*root(2, 3)*log(2)/3)/(5*log(2)) assert solve(5*x - 1 + 3*exp(2 - 7*x), x) == \ [Rational(1, 5) + LambertW(-21*exp(Rational(3, 5))/5)/7] assert solve((log(x) + x).subs(x, x**2 + 1)) == [ -I*sqrt(-LambertW(1) + 1), sqrt(-1 + LambertW(1))] # check collection ax = a**(3*x + 5) ans = solve(3*log(ax) + b*log(ax) + ax, x) x0 = 1/log(a) x1 = sqrt(3)*I x2 = b + 3 x3 = x2*LambertW(1/x2)/a**5 x4 = x3**Rational(1, 3)/2 assert ans == [ x0*log(x4*(-x1 - 1)), x0*log(x4*(x1 - 1)), x0*log(x3)/3] x1 = LambertW(Rational(1, 3)) x2 = a**(-5) x3 = -3**Rational(1, 3) x4 = 3**Rational(5, 6)*I x5 = x1**Rational(1, 3)*x2**Rational(1, 3)/2 ans = solve(3*log(ax) + ax, x) assert ans == [ x0*log(3*x1*x2)/3, x0*log(x5*(x3 - x4)), x0*log(x5*(x3 + x4))] # coverage p = symbols('p', positive=True) eq = 4*2**(2*p + 3) - 2*p - 3 assert _solve_lambert(eq, p, _filtered_gens(Poly(eq), p)) == [ Rational(-3, 2) - LambertW(-4*log(2))/(2*log(2))] assert set(solve(3**cos(x) - cos(x)**3)) == { acos(3), acos(-3*LambertW(-log(3)/3)/log(3))} # should give only one solution after using `uniq` assert solve(2*log(x) - 2*log(z) + log(z + log(x) + log(z)), x) == [ exp(-z + LambertW(2*z**4*exp(2*z))/2)/z] # cases when p != S.One # issue 4271 ans = solve((a/x + exp(x/2)).diff(x, 2), x) x0 = (-a)**Rational(1, 3) x1 = sqrt(3)*I x2 = x0/6 assert ans == [ 6*LambertW(x0/3), 6*LambertW(x2*(-x1 - 1)), 6*LambertW(x2*(x1 - 1))] assert solve((1/x + exp(x/2)).diff(x, 2), x) == \ [6*LambertW(Rational(-1, 3)), 6*LambertW(Rational(1, 6) - sqrt(3)*I/6), \ 6*LambertW(Rational(1, 6) + sqrt(3)*I/6), 6*LambertW(Rational(-1, 3), -1)] assert solve(x**2 - y**2/exp(x), x, y, dict=True) == \ [{x: 2*LambertW(-y/2)}, {x: 2*LambertW(y/2)}] # this is slow but not exceedingly slow assert solve((x**3)**(x/2) + pi/2, x) == [ exp(LambertW(-2*log(2)/3 + 2*log(pi)/3 + I*pi*Rational(2, 3)))]
def test_rewrite_trig(): assert solve(sin(x) + tan(x)) == [0, -pi, pi, 2*pi] assert solve(sin(x) + sec(x)) == [ -2*atan(Rational(-1, 2) + sqrt(2)*sqrt(1 - sqrt(3)*I)/2 + sqrt(3)*I/2), 2*atan(S.Half - sqrt(2)*sqrt(1 + sqrt(3)*I)/2 + sqrt(3)*I/2), 2*atan(S.Half + sqrt(2)*sqrt(1 + sqrt(3)*I)/2 + sqrt(3)*I/2), 2*atan(S.Half - sqrt(3)*I/2 + sqrt(2)*sqrt(1 - sqrt(3)*I)/2)] assert solve(sinh(x) + tanh(x)) == [0, I*pi]
# issue 6157 assert solve(2*sin(x) - cos(x), x) == [atan(S.Half)]
@XFAILdef test_rewrite_trigh(): # if this import passes then the test below should also pass from sympy.functions.elementary.hyperbolic import sech assert solve(sinh(x) + sech(x)) == [ 2*atanh(Rational(-1, 2) + sqrt(5)/2 - sqrt(-2*sqrt(5) + 2)/2), 2*atanh(Rational(-1, 2) + 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_uselogcombine(): eq = z - log(x) + log(y/(x*(-1 + y**2/x**2))) assert solve(eq, x, force=True) == [-sqrt(y*(y - exp(z))), sqrt(y*(y - exp(z)))] assert solve(log(x + 3) + log(1 + 3/x) - 3) in [ [-3 + sqrt(-12 + exp(3))*exp(Rational(3, 2))/2 + exp(3)/2, -sqrt(-12 + exp(3))*exp(Rational(3, 2))/2 - 3 + exp(3)/2], [-3 + sqrt(-36 + (-exp(3) + 6)**2)/2 + exp(3)/2, -3 - sqrt(-36 + (-exp(3) + 6)**2)/2 + exp(3)/2], ] assert solve(log(exp(2*x) + 1) + log(-tanh(x) + 1) - log(2)) == []
def test_atan2(): assert solve(atan2(x, 2) - pi/3, x) == [2*sqrt(3)]
def test_errorinverses(): assert solve(erf(x) - y, x) == [erfinv(y)] assert solve(erfinv(x) - y, x) == [erf(y)] assert solve(erfc(x) - y, x) == [erfcinv(y)] assert solve(erfcinv(x) - y, x) == [erfc(y)]
def test_issue_2725(): R = Symbol('R') eq = sqrt(2)*R*sqrt(1/(R + 1)) + (R + 1)*(sqrt(2)*sqrt(1/(R + 1)) - 1) sol = solve(eq, R, set=True)[1] assert sol == {(Rational(5, 3) + (Rational(-1, 2) - sqrt(3)*I/2)*(Rational(251, 27) + sqrt(111)*I/9)**Rational(1, 3) + 40/(9*((Rational(-1, 2) - sqrt(3)*I/2)*(Rational(251, 27) + sqrt(111)*I/9)**Rational(1, 3))),), (Rational(5, 3) + 40/(9*(Rational(251, 27) + sqrt(111)*I/9)**Rational(1, 3)) + (Rational(251, 27) + sqrt(111)*I/9)**Rational(1, 3),)}
def test_issue_5114_6611(): # See that it doesn't hang; this solves in about 2 seconds. # Also check that the solution is relatively small. # Note: the system in issue 6611 solves in about 5 seconds and has # an op-count of 138336 (with simplify=False). b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r = symbols('b:r') eqs = Matrix([ [b - c/d + r/d], [c*(1/g + 1/e + 1/d) - f/g - r/d], [-c/g + f*(1/j + 1/i + 1/g) - h/i], [-f/i + h*(1/m + 1/l + 1/i) - k/m], [-h/m + k*(1/p + 1/o + 1/m) - n/p], [-k/p + n*(1/q + 1/p)]]) v = Matrix([f, h, k, n, b, c]) ans = solve(list(eqs), list(v), simplify=False) # If time is taken to simplify then then 2617 below becomes # 1168 and the time is about 50 seconds instead of 2. assert sum([s.count_ops() for s in ans.values()]) <= 3270
def test_det_quick(): m = Matrix(3, 3, symbols('a:9')) assert m.det() == det_quick(m) # calls det_perm m[0, 0] = 1 assert m.det() == det_quick(m) # calls det_minor m = Matrix(3, 3, list(range(9))) assert m.det() == det_quick(m) # defaults to .det() # make sure they work with Sparse s = SparseMatrix(2, 2, (1, 2, 1, 4)) assert det_perm(s) == det_minor(s) == s.det()
def test_real_imag_splitting(): a, b = symbols('a b', real=True) assert solve(sqrt(a**2 + b**2) - 3, a) == \ [-sqrt(-b**2 + 9), sqrt(-b**2 + 9)] a, b = symbols('a b', imaginary=True) assert solve(sqrt(a**2 + b**2) - 3, a) == []
def test_issue_7110(): y = -2*x**3 + 4*x**2 - 2*x + 5 assert any(ask(Q.real(i)) for i in solve(y))
def test_units(): assert solve(1/x - 1/(2*cm)) == [2*cm]
def test_issue_7547(): A, B, V = symbols('A,B,V') eq1 = Eq(630.26*(V - 39.0)*V*(V + 39) - A + B, 0) eq2 = Eq(B, 1.36*10**8*(V - 39)) eq3 = Eq(A, 5.75*10**5*V*(V + 39.0)) sol = Matrix(nsolve(Tuple(eq1, eq2, eq3), [A, B, V], (0, 0, 0))) assert str(sol) == str(Matrix( [['4442890172.68209'], ['4289299466.1432'], ['70.5389666628177']]))
def test_issue_7895(): r = symbols('r', real=True) assert solve(sqrt(r) - 2) == [4]
def test_issue_2777(): # the equations represent two circles x, y = symbols('x y', real=True) e1, e2 = sqrt(x**2 + y**2) - 10, sqrt(y**2 + (-x + 10)**2) - 3 a, b = Rational(191, 20), 3*sqrt(391)/20 ans = [(a, -b), (a, b)] assert solve((e1, e2), (x, y)) == ans assert solve((e1, e2/(x - a)), (x, y)) == [] # make the 2nd circle's radius be -3 e2 += 6 assert solve((e1, e2), (x, y)) == [] assert solve((e1, e2), (x, y), check=False) == ans
def test_issue_7322(): number = 5.62527e-35 assert solve(x - number, x)[0] == number
def test_nsolve(): raises(ValueError, lambda: nsolve(x, (-1, 1), method='bisect')) raises(TypeError, lambda: nsolve((x - y + 3,x + y,z - y),(x,y,z),(-50,50))) raises(TypeError, lambda: nsolve((x + y, x - y), (0, 1)))
@slowdef test_high_order_multivariate(): assert len(solve(a*x**3 - x + 1, x)) == 3 assert len(solve(a*x**4 - x + 1, x)) == 4 assert solve(a*x**5 - x + 1, x) == [] # incomplete solution allowed raises(NotImplementedError, lambda: solve(a*x**5 - x + 1, x, incomplete=False))
# result checking must always consider the denominator and CRootOf # must be checked, too d = x**5 - x + 1 assert solve(d*(1 + 1/d)) == [CRootOf(d + 1, i) for i in range(5)] d = x - 1 assert solve(d*(2 + 1/d)) == [S.Half]
def test_base_0_exp_0(): assert solve(0**x - 1) == [0] assert solve(0**(x - 2) - 1) == [2] assert solve(S('x*(1/x**0 - x)', evaluate=False)) == \ [0, 1]
def test__simple_dens(): assert _simple_dens(1/x**0, [x]) == set() assert _simple_dens(1/x**y, [x]) == {x**y} assert _simple_dens(1/root(x, 3), [x]) == {x}
def test_issue_8755(): # This tests two things: that if full unrad is attempted and fails # the solution should still be found; also it tests the use of # keyword `composite`. assert len(solve(sqrt(y)*x + x**3 - 1, x)) == 3 assert len(solve(-512*y**3 + 1344*(x + 2)**Rational(1, 3)*y**2 - 1176*(x + 2)**Rational(2, 3)*y - 169*x + 686, y, _unrad=False)) == 3
@slowdef test_issue_8828(): x1 = 0 y1 = -620 r1 = 920 x2 = 126 y2 = 276 x3 = 51 y3 = 205 r3 = 104 v = x, y, z
f1 = (x - x1)**2 + (y - y1)**2 - (r1 - z)**2 f2 = (x2 - x)**2 + (y2 - y)**2 - z**2 f3 = (x - x3)**2 + (y - y3)**2 - (r3 - z)**2 F = f1,f2,f3
g1 = sqrt((x - x1)**2 + (y - y1)**2) + z - r1 g2 = f2 g3 = sqrt((x - x3)**2 + (y - y3)**2) + z - r3 G = g1,g2,g3
A = solve(F, v) B = solve(G, v) C = solve(G, v, manual=True)
p, q, r = [{tuple(i.evalf(2) for i in j) for j in R} for R in [A, B, C]] assert p == q == r
@slowdef test_issue_2840_8155(): assert solve(sin(3*x) + sin(6*x)) == [ 0, pi*Rational(-5, 3), pi*Rational(-4, 3), -pi, pi*Rational(-2, 3), pi*Rational(-4, 9), -pi/3, pi*Rational(-2, 9), pi*Rational(2, 9), pi/3, pi*Rational(4, 9), pi*Rational(2, 3), pi, pi*Rational(4, 3), pi*Rational(14, 9), pi*Rational(5, 3), pi*Rational(16, 9), 2*pi, -2*I*log(-(-1)**Rational(1, 9)), -2*I*log(-(-1)**Rational(2, 9)), -2*I*log(-sin(pi/18) - I*cos(pi/18)), -2*I*log(-sin(pi/18) + I*cos(pi/18)), -2*I*log(sin(pi/18) - I*cos(pi/18)), -2*I*log(sin(pi/18) + I*cos(pi/18))] assert solve(2*sin(x) - 2*sin(2*x)) == [ 0, pi*Rational(-5, 3), -pi, -pi/3, pi/3, pi, pi*Rational(5, 3)]
def test_issue_9567(): assert solve(1 + 1/(x - 1)) == [0]
def test_issue_11538(): assert solve(x + E) == [-E] assert solve(x**2 + E) == [-I*sqrt(E), I*sqrt(E)] assert solve(x**3 + 2*E) == [ -cbrt(2 * E), cbrt(2)*cbrt(E)/2 - cbrt(2)*sqrt(3)*I*cbrt(E)/2, cbrt(2)*cbrt(E)/2 + cbrt(2)*sqrt(3)*I*cbrt(E)/2] assert solve([x + 4, y + E], x, y) == {x: -4, y: -E} assert solve([x**2 + 4, y + E], x, y) == [ (-2*I, -E), (2*I, -E)]
e1 = x - y**3 + 4 e2 = x + y + 4 + 4 * E assert len(solve([e1, e2], x, y)) == 3
@slowdef test_issue_12114(): a, b, c, d, e, f, g = symbols('a,b,c,d,e,f,g') terms = [1 + a*b + d*e, 1 + a*c + d*f, 1 + b*c + e*f, g - a**2 - d**2, g - b**2 - e**2, g - c**2 - f**2] s = solve(terms, [a, b, c, d, e, f, g], dict=True) assert s == [{a: -sqrt(-f**2 - 1), b: -sqrt(-f**2 - 1), c: -sqrt(-f**2 - 1), d: f, e: f, g: -1}, {a: sqrt(-f**2 - 1), b: sqrt(-f**2 - 1), c: sqrt(-f**2 - 1), d: f, e: f, g: -1}, {a: -sqrt(3)*f/2 - sqrt(-f**2 + 2)/2, b: sqrt(3)*f/2 - sqrt(-f**2 + 2)/2, c: sqrt(-f**2 + 2), d: -f/2 + sqrt(-3*f**2 + 6)/2, e: -f/2 - sqrt(3)*sqrt(-f**2 + 2)/2, g: 2}, {a: -sqrt(3)*f/2 + sqrt(-f**2 + 2)/2, b: sqrt(3)*f/2 + sqrt(-f**2 + 2)/2, c: -sqrt(-f**2 + 2), d: -f/2 - sqrt(-3*f**2 + 6)/2, e: -f/2 + sqrt(3)*sqrt(-f**2 + 2)/2, g: 2}, {a: sqrt(3)*f/2 - sqrt(-f**2 + 2)/2, b: -sqrt(3)*f/2 - sqrt(-f**2 + 2)/2, c: sqrt(-f**2 + 2), d: -f/2 - sqrt(-3*f**2 + 6)/2, e: -f/2 + sqrt(3)*sqrt(-f**2 + 2)/2, g: 2}, {a: sqrt(3)*f/2 + sqrt(-f**2 + 2)/2, b: -sqrt(3)*f/2 + sqrt(-f**2 + 2)/2, c: -sqrt(-f**2 + 2), d: -f/2 + sqrt(-3*f**2 + 6)/2, e: -f/2 - sqrt(3)*sqrt(-f**2 + 2)/2, g: 2}]
def test_inf(): assert solve(1 - oo*x) == [] assert solve(oo*x, x) == [] assert solve(oo*x - oo, x) == []
def test_issue_12448(): f = Function('f') fun = [f(i) for i in range(15)] sym = symbols('x:15') reps = dict(zip(fun, sym))
(x, y, z), c = sym[:3], sym[3:] ssym = solve([c[4*i]*x + c[4*i + 1]*y + c[4*i + 2]*z + c[4*i + 3] for i in range(3)], (x, y, z))
(x, y, z), c = fun[:3], fun[3:] sfun = solve([c[4*i]*x + c[4*i + 1]*y + c[4*i + 2]*z + c[4*i + 3] for i in range(3)], (x, y, z))
assert sfun[fun[0]].xreplace(reps).count_ops() == \ ssym[sym[0]].count_ops()
def test_denoms(): assert denoms(x/2 + 1/y) == {2, y} assert denoms(x/2 + 1/y, y) == {y} assert denoms(x/2 + 1/y, [y]) == {y} assert denoms(1/x + 1/y + 1/z, [x, y]) == {x, y} assert denoms(1/x + 1/y + 1/z, x, y) == {x, y} assert denoms(1/x + 1/y + 1/z, {x, y}) == {x, y}
def test_issue_12476(): x0, x1, x2, x3, x4, x5 = symbols('x0 x1 x2 x3 x4 x5') eqns = [x0**2 - x0, x0*x1 - x1, x0*x2 - x2, x0*x3 - x3, x0*x4 - x4, x0*x5 - x5, x0*x1 - x1, -x0/3 + x1**2 - 2*x2/3, x1*x2 - x1/3 - x2/3 - x3/3, x1*x3 - x2/3 - x3/3 - x4/3, x1*x4 - 2*x3/3 - x5/3, x1*x5 - x4, x0*x2 - x2, x1*x2 - x1/3 - x2/3 - x3/3, -x0/6 - x1/6 + x2**2 - x2/6 - x3/3 - x4/6, -x1/6 + x2*x3 - x2/3 - x3/6 - x4/6 - x5/6, x2*x4 - x2/3 - x3/3 - x4/3, x2*x5 - x3, x0*x3 - x3, x1*x3 - x2/3 - x3/3 - x4/3, -x1/6 + x2*x3 - x2/3 - x3/6 - x4/6 - x5/6, -x0/6 - x1/6 - x2/6 + x3**2 - x3/3 - x4/6, -x1/3 - x2/3 + x3*x4 - x3/3, -x2 + x3*x5, x0*x4 - x4, x1*x4 - 2*x3/3 - x5/3, x2*x4 - x2/3 - x3/3 - x4/3, -x1/3 - x2/3 + x3*x4 - x3/3, -x0/3 - 2*x2/3 + x4**2, -x1 + x4*x5, x0*x5 - x5, x1*x5 - x4, x2*x5 - x3, -x2 + x3*x5, -x1 + x4*x5, -x0 + x5**2, x0 - 1] sols = [{x0: 1, x3: Rational(1, 6), x2: Rational(1, 6), x4: Rational(-2, 3), x1: Rational(-2, 3), x5: 1}, {x0: 1, x3: S.Half, x2: Rational(-1, 2), x4: 0, x1: 0, x5: -1}, {x0: 1, x3: Rational(-1, 3), x2: Rational(-1, 3), x4: Rational(1, 3), x1: Rational(1, 3), x5: 1}, {x0: 1, x3: 1, x2: 1, x4: 1, x1: 1, x5: 1}, {x0: 1, x3: Rational(-1, 3), x2: Rational(1, 3), x4: sqrt(5)/3, x1: -sqrt(5)/3, x5: -1}, {x0: 1, x3: Rational(-1, 3), x2: Rational(1, 3), x4: -sqrt(5)/3, x1: sqrt(5)/3, x5: -1}]
assert solve(eqns) == sols
def test_issue_13849(): t = symbols('t') assert solve((t*(sqrt(5) + sqrt(2)) - sqrt(2), t), t) == []
def test_issue_14860(): from sympy.physics.units import newton, kilo assert solve(8*kilo*newton + x + y, x) == [-8000*newton - y]
def test_issue_14721(): k, h, a, b = symbols(':4') assert solve([ -1 + (-k + 1)**2/b**2 + (-h - 1)**2/a**2, -1 + (-k + 1)**2/b**2 + (-h + 1)**2/a**2, h, k + 2], h, k, a, b) == [ (0, -2, -b*sqrt(1/(b**2 - 9)), b), (0, -2, b*sqrt(1/(b**2 - 9)), b)] assert solve([ h, h/a + 1/b**2 - 2, -h/2 + 1/b**2 - 2], a, h, b) == [ (a, 0, -sqrt(2)/2), (a, 0, sqrt(2)/2)] assert solve((a + b**2 - 1, a + b**2 - 2)) == []
def test_issue_14779(): x = symbols('x', real=True) assert solve(sqrt(x**4 - 130*x**2 + 1089) + sqrt(x**4 - 130*x**2 + 3969) - 96*Abs(x)/x,x) == [sqrt(130)]
def test_issue_15307(): assert solve((y - 2, Mul(x + 3,x - 2, evaluate=False))) == \ [{x: -3, y: 2}, {x: 2, y: 2}] assert solve((y - 2, Mul(3, x - 2, evaluate=False))) == \ {x: 2, y: 2} assert solve((y - 2, Add(x + 4, x - 2, evaluate=False))) == \ {x: -1, y: 2} eq1 = Eq(12513*x + 2*y - 219093, -5726*x - y) eq2 = Eq(-2*x + 8, 2*x - 40) assert solve([eq1, eq2]) == {x:12, y:75}
def test_issue_15415(): assert solve(x - 3, x) == [3] assert solve([x - 3], x) == {x:3} assert solve(Eq(y + 3*x**2/2, y + 3*x), y) == [] assert solve([Eq(y + 3*x**2/2, y + 3*x)], y) == [] assert solve([Eq(y + 3*x**2/2, y + 3*x), Eq(x, 1)], y) == []
@slowdef test_issue_15731(): # f(x)**g(x)=c assert solve(Eq((x**2 - 7*x + 11)**(x**2 - 13*x + 42), 1)) == [2, 3, 4, 5, 6, 7] assert solve((x)**(x + 4) - 4) == [-2] assert solve((-x)**(-x + 4) - 4) == [2] assert solve((x**2 - 6)**(x**2 - 2) - 4) == [-2, 2] assert solve((x**2 - 2*x - 1)**(x**2 - 3) - 1/(1 - 2*sqrt(2))) == [sqrt(2)] assert solve(x**(x + S.Half) - 4*sqrt(2)) == [S(2)] assert solve((x**2 + 1)**x - 25) == [2] assert solve(x**(2/x) - 2) == [2, 4] assert solve((x/2)**(2/x) - sqrt(2)) == [4, 8] assert solve(x**(x + S.Half) - Rational(9, 4)) == [Rational(3, 2)] # a**g(x)=c assert solve((-sqrt(sqrt(2)))**x - 2) == [4, log(2)/(log(2**Rational(1, 4)) + I*pi)] assert solve((sqrt(2))**x - sqrt(sqrt(2))) == [S.Half] assert solve((-sqrt(2))**x + 2*(sqrt(2))) == [3, (3*log(2)**2 + 4*pi**2 - 4*I*pi*log(2))/(log(2)**2 + 4*pi**2)] assert solve((sqrt(2))**x - 2*(sqrt(2))) == [3] assert solve(I**x + 1) == [2] assert solve((1 + I)**x - 2*I) == [2] assert solve((sqrt(2) + sqrt(3))**x - (2*sqrt(6) + 5)**Rational(1, 3)) == [Rational(2, 3)] # bases of both sides are equal b = Symbol('b') assert solve(b**x - b**2, x) == [2] assert solve(b**x - 1/b, x) == [-1] assert solve(b**x - b, x) == [1] b = Symbol('b', positive=True) assert solve(b**x - b**2, x) == [2] assert solve(b**x - 1/b, x) == [-1]
def test_issue_10933(): assert solve(x**4 + y*(x + 0.1), x) # doesn't fail assert solve(I*x**4 + x**3 + x**2 + 1.) # doesn't fail
def test_Abs_handling(): x = symbols('x', real=True) assert solve(abs(x/y), x) == [0]
def test_issue_7982(): x = Symbol('x') # Test that no exception happens assert solve([2*x**2 + 5*x + 20 <= 0, x >= 1.5], x) is S.false # From #8040 assert solve([x**3 - 8.08*x**2 - 56.48*x/5 - 106 >= 0, x - 1 <= 0], [x]) is S.false
def test_issue_14645(): x, y = symbols('x y') assert solve([x*y - x - y, x*y - x - y], [x, y]) == [(y/(y - 1), y)]
def test_issue_12024(): x, y = symbols('x y') assert solve(Piecewise((0.0, x < 0.1), (x, x >= 0.1)) - y) == \ [{y: Piecewise((0.0, x < 0.1), (x, True))}]
def test_issue_17452(): assert solve((7**x)**x + pi, x) == [-sqrt(log(pi) + I*pi)/sqrt(log(7)), sqrt(log(pi) + I*pi)/sqrt(log(7))] assert solve(x**(x/11) + pi/11, x) == [exp(LambertW(-11*log(11) + 11*log(pi) + 11*I*pi))]
def test_issue_17799(): assert solve(-erf(x**(S(1)/3))**pi + I, x) == []
def test_issue_17650(): x = Symbol('x', real=True) assert solve(abs(abs(x**2 - 1) - x) - x) == [1, -1 + sqrt(2), 1 + sqrt(2)]
def test_issue_17882(): eq = -8*x**2/(9*(x**2 - 1)**(S(4)/3)) + 4/(3*(x**2 - 1)**(S(1)/3)) assert unrad(eq) is None
def test_issue_17949(): assert solve(exp(+x+x**2), x) == [] assert solve(exp(-x+x**2), x) == [] assert solve(exp(+x-x**2), x) == [] assert solve(exp(-x-x**2), x) == []
def test_issue_10993(): assert solve(Eq(binomial(x, 2), 3)) == [-2, 3] assert solve(Eq(pow(x, 2) + binomial(x, 3), x)) == [-4, 0, 1] assert solve(Eq(binomial(x, 2), 0)) == [0, 1] assert solve(a+binomial(x, 3), a) == [-binomial(x, 3)] assert solve(x-binomial(a, 3) + binomial(y, 2) + sin(a), x) == [-sin(a) + binomial(a, 3) - binomial(y, 2)] assert solve((x+1)-binomial(x+1, 3), x) == [-2, -1, 3]
def test_issue_11553(): eq1 = x + y + 1 eq2 = x + GoldenRatio assert solve([eq1, eq2], x, y) == {x: -GoldenRatio, y: -1 + GoldenRatio} eq3 = x + 2 + TribonacciConstant assert solve([eq1, eq3], x, y) == {x: -2 - TribonacciConstant, y: 1 + TribonacciConstant}
def test_issue_19113_19102(): t = S(1)/3 solve(cos(x)**5-sin(x)**5) assert solve(4*cos(x)**3 - 2*sin(x)**3) == [ atan(2**(t)), -atan(2**(t)*(1 - sqrt(3)*I)/2), -atan(2**(t)*(1 + sqrt(3)*I)/2)] h = S.Half assert solve(cos(x)**2 + sin(x)) == [ 2*atan(-h + sqrt(5)/2 + sqrt(2)*sqrt(1 - sqrt(5))/2), -2*atan(h + sqrt(5)/2 + sqrt(2)*sqrt(1 + sqrt(5))/2), -2*atan(-sqrt(5)/2 + h + sqrt(2)*sqrt(1 - sqrt(5))/2), -2*atan(-sqrt(2)*sqrt(1 + sqrt(5))/2 + h + sqrt(5)/2)] assert solve(3*cos(x) - sin(x)) == [atan(3)]
def test_issue_19509(): a = S(3)/4 b = S(5)/8 c = sqrt(5)/8 d = sqrt(5)/4 assert solve(1/(x -1)**5 - 1) == [2, -d + a - sqrt(-b + c), -d + a + sqrt(-b + c), d + a - sqrt(-b - c), d + a + sqrt(-b - c)]
def test_issue_20747(): THT, HT, DBH, dib, c0, c1, c2, c3, c4 = symbols('THT HT DBH dib c0 c1 c2 c3 c4') f = DBH*c3 + THT*c4 + c2 rhs = 1 - ((HT - 1)/(THT - 1))**c1*(1 - exp(c0/f)) eq = dib - DBH*(c0 - f*log(rhs)) term = ((1 - exp((DBH*c0 - dib)/(DBH*(DBH*c3 + THT*c4 + c2)))) / (1 - exp(c0/(DBH*c3 + THT*c4 + c2)))) sol = [THT*term**(1/c1) - term**(1/c1) + 1] assert solve(eq, HT) == sol
def test_issue_20902(): f = (t / ((1 + t) ** 2)) assert solve(f.subs({t: 3 * x + 2}).diff(x) > 0, x) == (S(-1) < x) & (x < S(-1)/3) assert solve(f.subs({t: 3 * x + 3}).diff(x) > 0, x) == (S(-4)/3 < x) & (x < S(-2)/3) assert solve(f.subs({t: 3 * x + 4}).diff(x) > 0, x) == (S(-5)/3 < x) & (x < S(-1)) assert solve(f.subs({t: 3 * x + 2}).diff(x) > 0, x) == (S(-1) < x) & (x < S(-1)/3)
def test_issue_21034(): a = symbols('a', real=True) system = [x - cosh(cos(4)), y - sinh(cos(a)), z - tanh(x)] assert solve(system, x, y, z) == {x: cosh(cos(4)), z: tanh(cosh(cos(4))), y: sinh(cos(a))} #Constants inside hyperbolic functions should not be rewritten in terms of exp newsystem = [(exp(x) - exp(-x)) - tanh(x)*(exp(x) + exp(-x)) + x - 5] assert solve(newsystem, x) == {x: 5} #If the variable of interest is present in hyperbolic function, only then # it shouuld be rewritten in terms of exp and solved further
def test_issue_4886(): z = a*sqrt(R**2*a**2 + R**2*b**2 - c**2)/(a**2 + b**2) t = b*c/(a**2 + b**2) sol = [((b*(t - z) - c)/(-a), t - z), ((b*(t + z) - c)/(-a), t + z)] assert solve([x**2 + y**2 - R**2, a*x + b*y - c], x, y) == sol
def test_issue_6819(): a, b, c, d = symbols('a b c d', positive=True) assert solve(a*b**x - c*d**x, x) == [log(c/a)/log(b/d)]
def test_issue_17454(): x = Symbol('x') assert solve((1 - x - I)**4, x) == [1 - I]
def test_issue_21852(): solution = [21 - 21*sqrt(2)/2] assert solve(2*x + sqrt(2*x**2) - 21) == solution
def test_issue_21942(): eq = -d + (a*c**(1 - e) + b**(1 - e)*(1 - a))**(1/(1 - e)) sol = solve(eq, c, simplify=False, check=False) assert sol == [(b/b**e - b/(a*b**e) + d**(1 - e)/a)**(1/(1 - e))]
def test_solver_flags(): root = solve(x**5 + x**2 - x - 1, cubics=False) rad = solve(x**5 + x**2 - x - 1, cubics=True) assert root != rad
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