def test_GammaProcess_numeric(): t, d, x, y = symbols('t d x y', positive=True) X = GammaProcess("X", 1, 2) assert X.state_space == Interval(0, oo) assert X.index_set == Interval(0, oo) assert X.lamda == 1 assert X.gamma == 2 raises(ValueError, lambda: GammaProcess("X", -1, 2)) raises(ValueError, lambda: GammaProcess("X", 0, -2)) raises(ValueError, lambda: GammaProcess("X", -1, -2)) # all are independent because of non-overlapping intervals assert P((X(t) > 4) & (X(d) > 3) & (X(x) > 2) & (X(y) > 1), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Lopen(1, 2)) & Contains(x, Interval.Lopen(2, 3)) & Contains(y, Interval.Lopen(3, 4))).simplify() == \ 120*exp(-10) # Check working with Not and Or assert P( Not((X(t) < 5) & (X(d) > 3)), Contains(t, Interval.Ropen(2, 4)) & Contains(d, Interval.Lopen( 7, 8))).simplify() == -4 * exp(-3) + 472 * exp(-8) / 3 + 1 assert P((X(t) > 2) | (X(t) < 4), Contains(t, Interval.Ropen(1, 4))).simplify() == \ -643*exp(-4)/15 + 109*exp(-2)/15 + 1 assert E(X(t)) == 2 * t # E(X(t)) == gamma*t/l assert E(X(2) + x * E(X(5))) == 10 * x + 4
def test_reduce_rational_inequalities_real_relational(): assert reduce_rational_inequalities([], x) == False assert reduce_rational_inequalities( [[(x**2 + 3*x + 2)/(x**2 - 16) >= 0]], x, relational=False) == \ Union(Interval.open(-oo, -4), Interval(-2, -1), Interval.open(4, oo)) assert reduce_rational_inequalities( [[((-2*x - 10)*(3 - x))/((x**2 + 5)*(x - 2)**2) < 0]], x, relational=False) == \ Union(Interval.open(-5, 2), Interval.open(2, 3)) assert reduce_rational_inequalities([[(x + 1)/(x - 5) <= 0]], x, relational=False) == \ Interval.Ropen(-1, 5) assert reduce_rational_inequalities([[(x**2 + 4*x + 3)/(x - 1) > 0]], x, relational=False) == \ Union(Interval.open(-3, -1), Interval.open(1, oo)) assert reduce_rational_inequalities([[(x**2 - 16)/(x - 1)**2 < 0]], x, relational=False) == \ Union(Interval.open(-4, 1), Interval.open(1, 4)) assert reduce_rational_inequalities([[(3*x + 1)/(x + 4) >= 1]], x, relational=False) == \ Union(Interval.open(-oo, -4), Interval.Ropen(Rational(3, 2), oo)) assert reduce_rational_inequalities([[(x - 8)/x <= 3 - x]], x, relational=False) == \ Union(Interval.Lopen(-oo, -2), Interval.Lopen(0, 4)) # issue sympy/sympy#10237 assert reduce_rational_inequalities( [[x < oo, x >= 0, -oo < x]], x, relational=False) == Interval(0, oo)
def test_GammaProcess_symbolic(): t, d, x, y, g, l = symbols('t d x y g l', positive=True) X = GammaProcess("X", l, g) raises(NotImplementedError, lambda: X[t]) raises(IndexError, lambda: X(-1)) assert isinstance(X(t), RandomIndexedSymbol) assert X.state_space == Interval(0, oo) assert X.distribution(t) == GammaDistribution(g * t, 1 / l) assert X.joint_distribution(5, X(3)) == JointDistributionHandmade( Lambda( (X(5), X(3)), l**(8 * g) * exp(-l * X(3)) * exp(-l * X(5)) * X(3)**(3 * g - 1) * X(5)**(5 * g - 1) / (gamma(3 * g) * gamma(5 * g)))) # property of the gamma process at any given timestamp assert E(X(t)) == g * t / l assert variance(X(t)).simplify() == g * t / l**2 # Equivalent to E(2*X(1)) + E(X(1)**2) + E(X(1)**3), where E(X(1)) == g/l assert E(X(t)**2 + X(d)*2 + X(y)**3, Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Lopen(1, 2)) & Contains(y, Interval.Ropen(3, 4))) == \ 2*g/l + (g**2 + g)/l**2 + (g**3 + 3*g**2 + 2*g)/l**3 assert P(X(t) > 3, Contains(t, Interval.Lopen(3, 4))).simplify() == \ 1 - lowergamma(g, 3*l)/gamma(g) # equivalent to P(X(1)>3) #test issue 20078 assert (2 * X(t) + 3 * X(t)).simplify() == 5 * X(t) assert (2 * X(t) - 3 * X(t)).simplify() == -X(t) assert (2 * (0.25 * X(t))).simplify() == 0.5 * X(t) assert (2 * X(t) * 0.25 * X(t)).simplify() == 0.5 * X(t)**2 assert (X(t)**2 + X(t)**3).simplify() == (X(t) + 1) * X(t)**2
def test_normalize_theta_set(): # Interval assert normalize_theta_set(Interval(pi, 2*pi)) == \ Union(FiniteSet(0), Interval.Ropen(pi, 2*pi)) assert normalize_theta_set(Interval(9 * pi / 2, 5 * pi)) == Interval(pi / 2, pi) assert normalize_theta_set(Interval(-3 * pi / 2, pi / 2)) == Interval.Ropen(0, 2 * pi) assert normalize_theta_set(Interval.open(-3*pi/2, pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.open(pi/2, 2*pi)) assert normalize_theta_set(Interval.open(-7*pi/2, -3*pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.open(pi/2, 2*pi)) assert normalize_theta_set(Interval(-pi/2, pi/2)) == \ Union(Interval(0, pi/2), Interval.Ropen(3*pi/2, 2*pi)) assert normalize_theta_set(Interval.open(-pi/2, pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.open(3*pi/2, 2*pi)) assert normalize_theta_set(Interval(-4 * pi, 3 * pi)) == Interval.Ropen(0, 2 * pi) assert normalize_theta_set(Interval(-3 * pi / 2, -pi / 2)) == Interval( pi / 2, 3 * pi / 2) assert normalize_theta_set(Interval.open(0, 2 * pi)) == Interval.open( 0, 2 * pi) assert normalize_theta_set(Interval.Ropen(-pi/2, pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.Ropen(3*pi/2, 2*pi)) assert normalize_theta_set(Interval.Lopen(-pi/2, pi/2)) == \ Union(Interval(0, pi/2), Interval.open(3*pi/2, 2*pi)) assert normalize_theta_set(Interval(-pi/2, pi/2)) == \ Union(Interval(0, pi/2), Interval.Ropen(3*pi/2, 2*pi)) assert normalize_theta_set(Interval.open(4 * pi, 9 * pi / 2)) == Interval.open( 0, pi / 2) assert normalize_theta_set(Interval.Lopen(4 * pi, 9 * pi / 2)) == Interval.Lopen( 0, pi / 2) assert normalize_theta_set(Interval.Ropen(4 * pi, 9 * pi / 2)) == Interval.Ropen( 0, pi / 2) assert normalize_theta_set(Interval.open(3*pi, 5*pi)) == \ Union(Interval.Ropen(0, pi), Interval.open(pi, 2*pi)) # FiniteSet assert normalize_theta_set(FiniteSet(0, pi, 3 * pi)) == FiniteSet(0, pi) assert normalize_theta_set(FiniteSet(0, pi / 2, pi, 2 * pi)) == FiniteSet(0, pi / 2, pi) assert normalize_theta_set(FiniteSet(0, -pi / 2, -pi, -2 * pi)) == FiniteSet( 0, pi, 3 * pi / 2) assert normalize_theta_set(FiniteSet(-3*pi/2, pi/2)) == \ FiniteSet(pi/2) assert normalize_theta_set(FiniteSet(2 * pi)) == FiniteSet(0) # Unions assert normalize_theta_set(Union(Interval(0, pi/3), Interval(pi/2, pi))) == \ Union(Interval(0, pi/3), Interval(pi/2, pi)) assert normalize_theta_set(Union(Interval(0, pi), Interval(2*pi, 7*pi/3))) == \ Interval(0, pi) # ValueError for non-real sets raises(ValueError, lambda: normalize_theta_set(S.Complexes))
def test_WienerProcess(): X = WienerProcess("X") assert X.state_space == S.Reals assert X.index_set == Interval(0, oo) t, d, x, y = symbols('t d x y', positive=True) assert isinstance(X(t), RandomIndexedSymbol) assert X.distribution(t) == NormalDistribution(0, sqrt(t)) with warns_deprecated_sympy(): X.distribution(X(t)) raises(ValueError, lambda: PoissonProcess("X", -1)) raises(NotImplementedError, lambda: X[t]) raises(IndexError, lambda: X(-2)) assert X.joint_distribution(X(2), X(3)) == JointDistributionHandmade( Lambda((X(2), X(3)), sqrt(6) * exp(-X(2)**2 / 4) * exp(-X(3)**2 / 6) / (12 * pi))) assert X.joint_distribution(4, 6) == JointDistributionHandmade( Lambda((X(4), X(6)), sqrt(6) * exp(-X(4)**2 / 8) * exp(-X(6)**2 / 12) / (24 * pi))) assert P(X(t) < 3).simplify() == erf(3 * sqrt(2) / (2 * sqrt(t))) / 2 + S(1) / 2 assert P(X(t) > 2, Contains(t, Interval.Lopen(3, 7))).simplify() == S(1)/2 -\ erf(sqrt(2)/2)/2 # Equivalent to P(X(1)>1)**4 assert P((X(t) > 4) & (X(d) > 3) & (X(x) > 2) & (X(y) > 1), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Lopen(1, 2)) & Contains(x, Interval.Lopen(2, 3)) & Contains(y, Interval.Lopen(3, 4))).simplify() ==\ (1 - erf(sqrt(2)/2))*(1 - erf(sqrt(2)))*(1 - erf(3*sqrt(2)/2))*(1 - erf(2*sqrt(2)))/16 # Contains an overlapping interval so, return Probability assert P((X(t) < 2) & (X(d) > 3), Contains(t, Interval.Lopen(0, 2)) & Contains(d, Interval.Ropen(2, 4))) == Probability( (X(d) > 3) & (X(t) < 2), Contains(d, Interval.Ropen(2, 4)) & Contains(t, Interval.Lopen(0, 2))) assert str(P(Not((X(t) < 5) & (X(d) > 3)), Contains(t, Interval.Ropen(2, 4)) & Contains(d, Interval.Lopen(7, 8))).simplify()) == \ '-(1 - erf(3*sqrt(2)/2))*(2 - erfc(5/2))/4 + 1' # Distribution has mean 0 at each timestamp assert E(X(t)) == 0 assert E( x * (X(t) + X(d)) * (X(t)**2 + X(d)**2), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Ropen(1, 2))) == Expectation( x * (X(d) + X(t)) * (X(d)**2 + X(t)**2), Contains(d, Interval.Ropen(1, 2)) & Contains(t, Interval.Lopen(0, 1))) assert E(X(t) + x * E(X(3))) == 0 #test issue 20078 assert (2 * X(t) + 3 * X(t)).simplify() == 5 * X(t) assert (2 * X(t) - 3 * X(t)).simplify() == -X(t) assert (2 * (0.25 * X(t))).simplify() == 0.5 * X(t) assert (2 * X(t) * 0.25 * X(t)).simplify() == 0.5 * X(t)**2 assert (X(t)**2 + X(t)**3).simplify() == (X(t) + 1) * X(t)**2
def test_normalize_theta_set(): # Interval assert normalize_theta_set(Interval(pi, 2*pi)) == \ Union(FiniteSet(0), Interval.Ropen(pi, 2*pi)) assert normalize_theta_set(Interval(pi*Rational(9, 2), 5*pi)) == Interval(pi/2, pi) assert normalize_theta_set(Interval(pi*Rational(-3, 2), pi/2)) == Interval.Ropen(0, 2*pi) assert normalize_theta_set(Interval.open(pi*Rational(-3, 2), pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.open(pi/2, 2*pi)) assert normalize_theta_set(Interval.open(pi*Rational(-7, 2), pi*Rational(-3, 2))) == \ Union(Interval.Ropen(0, pi/2), Interval.open(pi/2, 2*pi)) assert normalize_theta_set(Interval(-pi/2, pi/2)) == \ Union(Interval(0, pi/2), Interval.Ropen(pi*Rational(3, 2), 2*pi)) assert normalize_theta_set(Interval.open(-pi/2, pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.open(pi*Rational(3, 2), 2*pi)) assert normalize_theta_set(Interval(-4*pi, 3*pi)) == Interval.Ropen(0, 2*pi) assert normalize_theta_set(Interval(pi*Rational(-3, 2), -pi/2)) == Interval(pi/2, pi*Rational(3, 2)) assert normalize_theta_set(Interval.open(0, 2*pi)) == Interval.open(0, 2*pi) assert normalize_theta_set(Interval.Ropen(-pi/2, pi/2)) == \ Union(Interval.Ropen(0, pi/2), Interval.Ropen(pi*Rational(3, 2), 2*pi)) assert normalize_theta_set(Interval.Lopen(-pi/2, pi/2)) == \ Union(Interval(0, pi/2), Interval.open(pi*Rational(3, 2), 2*pi)) assert normalize_theta_set(Interval(-pi/2, pi/2)) == \ Union(Interval(0, pi/2), Interval.Ropen(pi*Rational(3, 2), 2*pi)) assert normalize_theta_set(Interval.open(4*pi, pi*Rational(9, 2))) == Interval.open(0, pi/2) assert normalize_theta_set(Interval.Lopen(4*pi, pi*Rational(9, 2))) == Interval.Lopen(0, pi/2) assert normalize_theta_set(Interval.Ropen(4*pi, pi*Rational(9, 2))) == Interval.Ropen(0, pi/2) assert normalize_theta_set(Interval.open(3*pi, 5*pi)) == \ Union(Interval.Ropen(0, pi), Interval.open(pi, 2*pi)) # FiniteSet assert normalize_theta_set(FiniteSet(0, pi, 3*pi)) == FiniteSet(0, pi) assert normalize_theta_set(FiniteSet(0, pi/2, pi, 2*pi)) == FiniteSet(0, pi/2, pi) assert normalize_theta_set(FiniteSet(0, -pi/2, -pi, -2*pi)) == FiniteSet(0, pi, pi*Rational(3, 2)) assert normalize_theta_set(FiniteSet(pi*Rational(-3, 2), pi/2)) == \ FiniteSet(pi/2) assert normalize_theta_set(FiniteSet(2*pi)) == FiniteSet(0) # Unions assert normalize_theta_set(Union(Interval(0, pi/3), Interval(pi/2, pi))) == \ Union(Interval(0, pi/3), Interval(pi/2, pi)) assert normalize_theta_set(Union(Interval(0, pi), Interval(2*pi, pi*Rational(7, 3)))) == \ Interval(0, pi) # ValueError for non-real sets raises(ValueError, lambda: normalize_theta_set(S.Complexes)) # NotImplementedError for subset of reals raises(NotImplementedError, lambda: normalize_theta_set(Interval(0, 1))) # NotImplementedError without pi as coefficient raises(NotImplementedError, lambda: normalize_theta_set(Interval(1, 2*pi))) raises(NotImplementedError, lambda: normalize_theta_set(Interval(2*pi, 10))) raises(NotImplementedError, lambda: normalize_theta_set(FiniteSet(0, 3, 3*pi)))
def test_integers(): Z = S.Integers assert 5 in Z assert -5 in Z assert 5.5 not in Z assert not Z.contains(oo) assert not Z.contains(-oo) zi = iter(Z) a, b, c, d = next(zi), next(zi), next(zi), next(zi) assert (a, b, c, d) == (0, 1, -1, 2) assert isinstance(a, Basic) assert Z.intersect(Interval(-5, 5)) == Range(-5, 6) assert Z.intersect(Interval(-5, 5, True, True)) == Range(-4, 5) assert Z.intersect(Interval(5, S.Infinity)) == Range(5, S.Infinity) assert Z.intersect(Interval.Lopen(5, S.Infinity)) == Range(6, S.Infinity) assert Z.inf is -oo assert Z.sup is oo assert Z.boundary == Z assert Z.is_open == False assert Z.is_closed == True assert Z.as_relational(x) == And(Eq(floor(x), x), -oo < x, x < oo)
def test_is_convex(): assert is_convex(1/x, x, domain=Interval.open(0, oo)) == True assert is_convex(1/x, x, domain=Interval(-oo, 0)) == False assert is_convex(x**2, x, domain=Interval(0, oo)) == True assert is_convex(1/x**3, x, domain=Interval.Lopen(0, oo)) == True assert is_convex(-1/x**3, x, domain=Interval.Ropen(-oo, 0)) == True assert is_convex(log(x), x) == False raises(NotImplementedError, lambda: is_convex(log(x), x, a))
def test_integers(): Z = S.Integers assert 5 in Z assert -5 in Z assert 5.5 not in Z zi = iter(Z) a, b, c, d = next(zi), next(zi), next(zi), next(zi) assert (a, b, c, d) == (0, 1, -1, 2) assert isinstance(a, Basic) assert Z.intersect(Interval(-5, 5)) == Range(-5, 6) assert Z.intersect(Interval(-5, 5, True, True)) == Range(-4, 5) assert Z.intersect(Interval(5, S.Infinity)) == Range(5, S.Infinity) assert Z.intersect(Interval.Lopen(5, S.Infinity)) == Range(6, S.Infinity) assert Z.inf == -oo assert Z.sup == oo assert Z.boundary == Z
def test_PoissonProcess(): X = PoissonProcess("X", 3) assert X.state_space == S.Naturals0 assert X.index_set == Interval(0, oo) assert X.lamda == 3 t, d, x, y = symbols('t d x y', positive=True) assert isinstance(X(t), RandomIndexedSymbol) assert X.distribution(t) == PoissonDistribution(3 * t) raises(ValueError, lambda: PoissonProcess("X", -1)) raises(NotImplementedError, lambda: X[t]) raises(IndexError, lambda: X(-5)) assert X.joint_distribution(X(2), X(3)) == JointDistributionHandmade( Lambda((X(2), X(3)), 6**X(2) * 9**X(3) * exp(-15) / (factorial(X(2)) * factorial(X(3))))) assert X.joint_distribution(4, 6) == JointDistributionHandmade( Lambda((X(4), X(6)), 12**X(4) * 18**X(6) * exp(-30) / (factorial(X(4)) * factorial(X(6))))) assert P(X(t) < 1) == exp(-3 * t) assert P(Eq(X(t), 0), Contains(t, Interval.Lopen(3, 5))) == exp(-6) # exp(-2*lamda) res = P(Eq(X(t), 1), Contains(t, Interval.Lopen(3, 4))) assert res == 3 * exp(-3) # Equivalent to P(Eq(X(t), 1))**4 because of non-overlapping intervals assert P( Eq(X(t), 1) & Eq(X(d), 1) & Eq(X(x), 1) & Eq(X(y), 1), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Lopen(1, 2)) & Contains(x, Interval.Lopen(2, 3)) & Contains(y, Interval.Lopen(3, 4))) == res**4 # Return Probability because of overlapping intervals assert P(Eq(X(t), 2) & Eq(X(d), 3), Contains(t, Interval.Lopen(0, 2)) & Contains(d, Interval.Ropen(2, 4))) == \ Probability(Eq(X(d), 3) & Eq(X(t), 2), Contains(t, Interval.Lopen(0, 2)) & Contains(d, Interval.Ropen(2, 4))) raises(ValueError, lambda: P( Eq(X(t), 2) & Eq(X(d), 3), Contains(t, Interval.Lopen(0, 4)) & Contains(d, Interval.Lopen(3, oo))) ) # no bound on d assert P(Eq(X(3), 2)) == 81 * exp(-9) / 2 assert P(Eq(X(t), 2), Contains(t, Interval.Lopen(0, 5))) == 225 * exp(-15) / 2 # Check that probability works correctly by adding it to 1 res1 = P(X(t) <= 3, Contains(t, Interval.Lopen(0, 5))) res2 = P(X(t) > 3, Contains(t, Interval.Lopen(0, 5))) assert res1 == 691 * exp(-15) assert (res1 + res2).simplify() == 1 # Check Not and Or assert P(Not(Eq(X(t), 2) & (X(d) > 3)), Contains(t, Interval.Ropen(2, 4)) & \ Contains(d, Interval.Lopen(7, 8))).simplify() == -18*exp(-6) + 234*exp(-9) + 1 assert P(Eq(X(t), 2) | Ne(X(t), 4), Contains(t, Interval.Ropen(2, 4))) == 1 - 36 * exp(-6) raises(ValueError, lambda: P(X(t) > 2, X(t) + X(d))) assert E( X(t)) == 3 * t # property of the distribution at a given timestamp assert E( X(t)**2 + X(d) * 2 + X(y)**3, Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Lopen(1, 2)) & Contains(y, Interval.Ropen(3, 4))) == 75 assert E(X(t)**2, Contains(t, Interval.Lopen(0, 1))) == 12 assert E(x*(X(t) + X(d))*(X(t)**2+X(d)**2), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Ropen(1, 2))) == \ Expectation(x*(X(d) + X(t))*(X(d)**2 + X(t)**2), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Ropen(1, 2))) # Value Error because of infinite time bound raises(ValueError, lambda: E(X(t)**3, Contains(t, Interval.Lopen(1, oo)))) # Equivalent to E(X(t)**2) - E(X(d)**2) == E(X(1)**2) - E(X(1)**2) == 0 assert E((X(t) + X(d)) * (X(t) - X(d)), Contains(t, Interval.Lopen(0, 1)) & Contains(d, Interval.Lopen(1, 2))) == 0 assert E(X(2) + x * E(X(5))) == 15 * x + 6 assert E(x * X(1) + y) == 3 * x + y assert P(Eq(X(1), 2) & Eq(X(t), 3), Contains(t, Interval.Lopen(1, 2))) == 81 * exp(-6) / 4 Y = PoissonProcess("Y", 6) Z = X + Y assert Z.lamda == X.lamda + Y.lamda == 9 raises(ValueError, lambda: X + 5) # should be added be only PoissonProcess instance N, M = Z.split(4, 5) assert N.lamda == 4 assert M.lamda == 5 raises(ValueError, lambda: Z.split(3, 2)) # 2+3 != 9 raises( ValueError, lambda: P(Eq(X(t), 0), Contains(t, Interval.Lopen(1, 3)) & Eq(X(1), 0))) # check if it handles queries with two random variables in one args res1 = P(Eq(N(3), N(5))) assert res1 == P(Eq(N(t), 0), Contains(t, Interval(3, 5))) res2 = P(N(3) > N(1)) assert res2 == P((N(t) > 0), Contains(t, Interval(1, 3))) assert P(N(3) < N(1)) == 0 # condition is not possible res3 = P(N(3) <= N(1)) # holds only for Eq(N(3), N(1)) assert res3 == P(Eq(N(t), 0), Contains(t, Interval(1, 3))) # tests from https://www.probabilitycourse.com/chapter11/11_1_2_basic_concepts_of_the_poisson_process.php X = PoissonProcess('X', 10) # 11.1 assert P(Eq(X(S(1) / 3), 3) & Eq(X(1), 10)) == exp(-10) * Rational(8000000000, 11160261) assert P(Eq(X(1), 1), Eq(X(S(1) / 3), 3)) == 0 assert P(Eq(X(1), 10), Eq(X(S(1) / 3), 3)) == P(Eq(X(S(2) / 3), 7)) X = PoissonProcess('X', 2) # 11.2 assert P(X(S(1) / 2) < 1) == exp(-1) assert P(X(3) < 1, Eq(X(1), 0)) == exp(-4) assert P(Eq(X(4), 3), Eq(X(2), 3)) == exp(-4) X = PoissonProcess('X', 3) assert P(Eq(X(2), 5) & Eq(X(1), 2)) == Rational(81, 4) * exp(-6) # check few properties assert P( X(2) <= 3, X(1) >= 1) == 3 * P(Eq(X(1), 0)) + 2 * P(Eq(X(1), 1)) + P(Eq(X(1), 2)) assert P(X(2) <= 3, X(1) > 1) == 2 * P(Eq(X(1), 0)) + 1 * P(Eq(X(1), 1)) assert P(Eq(X(2), 5) & Eq(X(1), 2)) == P(Eq(X(1), 3)) * P(Eq(X(1), 2)) assert P(Eq(X(3), 4), Eq(X(1), 3)) == P(Eq(X(2), 1)) #test issue 20078 assert (2 * X(t) + 3 * X(t)).simplify() == 5 * X(t) assert (2 * X(t) - 3 * X(t)).simplify() == -X(t) assert (2 * (0.25 * X(t))).simplify() == 0.5 * X(t) assert (2 * X(t) * 0.25 * X(t)).simplify() == 0.5 * X(t)**2 assert (X(t)**2 + X(t)**3).simplify() == (X(t) + 1) * X(t)**2
def solve_univariate_inequality(expr, gen, relational=True, domain=S.Reals, continuous=False): """Solves a real univariate inequality. Parameters ========== expr : Relational The target inequality gen : Symbol The variable for which the inequality is solved relational : bool A Relational type output is expected or not domain : Set The domain over which the equation is solved continuous: bool True if expr is known to be continuous over the given domain (and so continuous_domain() doesn't need to be called on it) Raises ====== NotImplementedError The solution of the inequality cannot be determined due to limitation in :func:`sympy.solvers.solveset.solvify`. Notes ===== Currently, we cannot solve all the inequalities due to limitations in :func:`sympy.solvers.solveset.solvify`. Also, the solution returned for trigonometric inequalities are restricted in its periodic interval. See Also ======== sympy.solvers.solveset.solvify: solver returning solveset solutions with solve's output API Examples ======== >>> from sympy import solve_univariate_inequality, Symbol, sin, Interval, S >>> x = Symbol('x') >>> solve_univariate_inequality(x**2 >= 4, x) ((2 <= x) & (x < oo)) | ((-oo < x) & (x <= -2)) >>> solve_univariate_inequality(x**2 >= 4, x, relational=False) Union(Interval(-oo, -2), Interval(2, oo)) >>> domain = Interval(0, S.Infinity) >>> solve_univariate_inequality(x**2 >= 4, x, False, domain) Interval(2, oo) >>> solve_univariate_inequality(sin(x) > 0, x, relational=False) Interval.open(0, pi) """ from sympy.solvers.solvers import denoms if domain.is_subset(S.Reals) is False: raise NotImplementedError( filldedent(''' Inequalities in the complex domain are not supported. Try the real domain by setting domain=S.Reals''')) elif domain is not S.Reals: rv = solve_univariate_inequality( expr, gen, relational=False, continuous=continuous).intersection(domain) if relational: rv = rv.as_relational(gen) return rv else: pass # continue with attempt to solve in Real domain # This keeps the function independent of the assumptions about `gen`. # `solveset` makes sure this function is called only when the domain is # real. _gen = gen _domain = domain if gen.is_extended_real is False: rv = S.EmptySet return rv if not relational else rv.as_relational(_gen) elif gen.is_extended_real is None: gen = Dummy('gen', extended_real=True) try: expr = expr.xreplace({_gen: gen}) except TypeError: raise TypeError( filldedent(''' When gen is real, the relational has a complex part which leads to an invalid comparison like I < 0. ''')) rv = None if expr is S.true: rv = domain elif expr is S.false: rv = S.EmptySet else: e = expr.lhs - expr.rhs period = periodicity(e, gen) if period == S.Zero: e = expand_mul(e) const = expr.func(e, 0) if const is S.true: rv = domain elif const is S.false: rv = S.EmptySet elif period is not None: frange = function_range(e, gen, domain) rel = expr.rel_op if rel in ('<', '<='): if expr.func(frange.sup, 0): rv = domain elif not expr.func(frange.inf, 0): rv = S.EmptySet elif rel in ('>', '>='): if expr.func(frange.inf, 0): rv = domain elif not expr.func(frange.sup, 0): rv = S.EmptySet inf, sup = domain.inf, domain.sup if sup - inf is S.Infinity: domain = Interval(0, period, False, True).intersect(_domain) _domain = domain if rv is None: n, d = e.as_numer_denom() try: if gen not in n.free_symbols and len(e.free_symbols) > 1: raise ValueError # this might raise ValueError on its own # or it might give None... solns = solvify(e, gen, domain) if solns is None: # in which case we raise ValueError raise ValueError except (ValueError, NotImplementedError): # replace gen with generic x since it's # univariate anyway raise NotImplementedError( filldedent(''' The inequality, %s, cannot be solved using solve_univariate_inequality. ''' % expr.subs(gen, Symbol('x')))) expanded_e = expand_mul(e) def valid(x): # this is used to see if gen=x satisfies the # relational by substituting it into the # expanded form and testing against 0, e.g. # if expr = x*(x + 1) < 2 then e = x*(x + 1) - 2 # and expanded_e = x**2 + x - 2; the test is # whether a given value of x satisfies # x**2 + x - 2 < 0 # # expanded_e, expr and gen used from enclosing scope v = expanded_e.subs(gen, expand_mul(x)) try: r = expr.func(v, 0) except TypeError: r = S.false if r in (S.true, S.false): return r if v.is_extended_real is False: return S.false else: v = v.n(2) if v.is_comparable: return expr.func(v, 0) # not comparable or couldn't be evaluated raise NotImplementedError( 'relationship did not evaluate: %s' % r) singularities = [] for d in denoms(expr, gen): singularities.extend(solvify(d, gen, domain)) if not continuous: domain = continuous_domain(expanded_e, gen, domain) include_x = '=' in expr.rel_op and expr.rel_op != '!=' try: discontinuities = set(domain.boundary - FiniteSet(domain.inf, domain.sup)) # remove points that are not between inf and sup of domain critical_points = FiniteSet( *(solns + singularities + list(discontinuities))).intersection( Interval(domain.inf, domain.sup, domain.inf not in domain, domain.sup not in domain)) if all(r.is_number for r in critical_points): reals = _nsort(critical_points, separated=True)[0] else: sifted = sift(critical_points, lambda x: x.is_extended_real) if sifted[None]: # there were some roots that weren't known # to be real raise NotImplementedError try: reals = sifted[True] if len(reals) > 1: reals = list(sorted(reals)) except TypeError: raise NotImplementedError except NotImplementedError: raise NotImplementedError( 'sorting of these roots is not supported') # If expr contains imaginary coefficients, only take real # values of x for which the imaginary part is 0 make_real = S.Reals if im(expanded_e) != S.Zero: check = True im_sol = FiniteSet() try: a = solveset(im(expanded_e), gen, domain) if not isinstance(a, Interval): for z in a: if z not in singularities and valid( z) and z.is_extended_real: im_sol += FiniteSet(z) else: start, end = a.inf, a.sup for z in _nsort(critical_points + FiniteSet(end)): valid_start = valid(start) if start != end: valid_z = valid(z) pt = _pt(start, z) if pt not in singularities and pt.is_extended_real and valid( pt): if valid_start and valid_z: im_sol += Interval(start, z) elif valid_start: im_sol += Interval.Ropen(start, z) elif valid_z: im_sol += Interval.Lopen(start, z) else: im_sol += Interval.open(start, z) start = z for s in singularities: im_sol -= FiniteSet(s) except (TypeError): im_sol = S.Reals check = False if im_sol is S.EmptySet: raise ValueError( filldedent(''' %s contains imaginary parts which cannot be made 0 for any value of %s satisfying the inequality, leading to relations like I < 0. ''' % (expr.subs(gen, _gen), _gen))) make_real = make_real.intersect(im_sol) sol_sets = [S.EmptySet] start = domain.inf if start in domain and valid(start) and start.is_finite: sol_sets.append(FiniteSet(start)) for x in reals: end = x if valid(_pt(start, end)): sol_sets.append(Interval(start, end, True, True)) if x in singularities: singularities.remove(x) else: if x in discontinuities: discontinuities.remove(x) _valid = valid(x) else: # it's a solution _valid = include_x if _valid: sol_sets.append(FiniteSet(x)) start = end end = domain.sup if end in domain and valid(end) and end.is_finite: sol_sets.append(FiniteSet(end)) if valid(_pt(start, end)): sol_sets.append(Interval.open(start, end)) if im(expanded_e) != S.Zero and check: rv = (make_real).intersect(_domain) else: rv = Intersection((Union(*sol_sets)), make_real, _domain).subs(gen, _gen) return rv if not relational else rv.as_relational(_gen)
def test_issue_10671_12466(): assert solveset(sin(y), y, Interval(0, pi)) == FiniteSet(0, pi) i = Interval(1, 10) assert solveset((1/x).diff(x) < 0, x, i) == i assert solveset((log(x - 6)/x) <= 0, x, S.Reals) == \ Interval.Lopen(6, 7)