from sympy import ( Abs, And, Derivative, Dummy, Eq, Float, Function, Gt, I, Integral, LambertW, Lt, Matrix, Or, Poly, Q, Rational, S, Symbol, Ne, Wild, acos, asin, atan, atanh, binomial, cos, cosh, diff, erf, erfinv, erfc, erfcinv, exp, im, log, pi, re, sec, sin, sinh, solve, solve_linear, sqrt, sstr, symbols, sympify, tan, tanh, root, atan2, arg, Mul, SparseMatrix, ask, Tuple, nsolve, oo, E, cbrt, denom, Add, Piecewise, GoldenRatio, TribonacciConstant) from sympy.core.function import nfloat from sympy.solvers import solve_linear_system, solve_linear_system_LU, \ solve_undetermined_coeffs from sympy.solvers.bivariate import _filtered_gens, _solve_lambert, _lambert from sympy.solvers.solvers import _invert, unrad, checksol, posify, _ispow, \ det_quick, det_perm, det_minor, _simple_dens, denoms from sympy.physics.units import cm from sympy.polys.rootoftools import CRootOf from sympy.testing.pytest import slow, XFAIL, SKIP, raises from sympy.testing.randtest 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]) == [] # 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 solve([y, exp(x) + x], x, y) == [(-LambertW(1), 0)] # 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_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} @XFAIL def 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 @slow def 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) ans = [(log(2401) + 5*LambertW((-1 + sqrt(5) + sqrt(2)*I*sqrt(sqrt(5) + \ 5))*log(7**(7*3**Rational(1, 5)/20))* -1))/(-3*log(7)), \ (log(2401) + 5*LambertW((1 + sqrt(5) - sqrt(2)*I*sqrt(5 - \ sqrt(5)))*log(7**(7*3**Rational(1, 5)/20))))/(-3*log(7)), \ (log(2401) + 5*LambertW((1 + sqrt(5) + sqrt(2)*I*sqrt(5 - \ sqrt(5)))*log(7**(7*3**Rational(1, 5)/20))))/(-3*log(7)), \ (log(2401) + 5*LambertW((-sqrt(5) + 1 + sqrt(2)*I*sqrt(sqrt(5) + \ 5))*log(7**(7*3**Rational(1, 5)/20))))/(-3*log(7)), \ (log(2401) + 5*LambertW(-log(7**(7*3**Rational(1, 5)/5))))/(-3*log(7))] assert result == ans # 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)) @slow def 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 @slow def 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] @XFAIL def 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] @slow def 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] @XFAIL def 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)} @slow def 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)] @XFAIL def test_rewrite_trigh(): # if this import passes then the test below should also pass from sympy 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))) @slow def 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 @slow def 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 @slow def 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 @slow def 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) == [] @slow def 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_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))]