def integrate(self, x=None, **kwargs): """Integrate Formal Power Series. Examples ======== >>> from sympy import fps, sin, integrate >>> from sympy.abc import x >>> f = fps(sin(x)) >>> f.integrate(x).truncate() -1 + x**2/2 - x**4/24 + O(x**6) >>> integrate(f, (x, 0, 1)) -cos(1) + 1 """ from sympy.integrals import integrate if x is None: x = self.x elif iterable(x): return integrate(self.function, x) f = integrate(self.function, x) ind = integrate(self.ind, x) ind += (f - ind).limit(x, 0) # constant of integration pow_xk = self._get_pow_x(self.xk.formula) ak = self.ak k = ak.variables[0] if ak.formula.has(x): form = [] for e, c in ak.formula.args: temp = S.Zero for t in Add.make_args(e): pow_x = self._get_pow_x(t) temp += t / (pow_xk + pow_x + 1) form.append((temp, c)) form = Piecewise(*form) ak = sequence(form.subs(k, k - 1), (k, ak.start + 1, ak.stop)) else: ak = sequence((ak.formula / (pow_xk + 1)).subs(k, k - 1), (k, ak.start + 1, ak.stop)) return self.func(f, self.x, self.x0, self.dir, (ak, self.xk, ind))
def _eval_derivative(self, x): f = self.function.diff(x) ind = self.ind.diff(x) pow_xk = self._get_pow_x(self.xk.formula) ak = self.ak k = ak.variables[0] if ak.formula.has(x): form = [] for e, c in ak.formula.args: temp = S.Zero for t in Add.make_args(e): pow_x = self._get_pow_x(t) temp += t * (pow_xk + pow_x) form.append((temp, c)) form = Piecewise(*form) ak = sequence(form.subs(k, k + 1), (k, ak.start - 1, ak.stop)) else: ak = sequence((ak.formula * pow_xk).subs(k, k + 1), (k, ak.start - 1, ak.stop)) return self.func(f, self.x, self.x0, self.dir, (ak, self.xk, ind))
def rsolve_hypergeometric(f, x, P, Q, k, m): """Solves RE of hypergeometric type. Attempts to solve RE of the form Q(k)*a(k + m) - P(k)*a(k) Transformations that preserve Hypergeometric type: a. x**n*f(x): b(k + m) = R(k - n)*b(k) b. f(A*x): b(k + m) = A**m*R(k)*b(k) c. f(x**n): b(k + n*m) = R(k/n)*b(k) d. f(x**(1/m)): b(k + 1) = R(k*m)*b(k) e. f'(x): b(k + m) = ((k + m + 1)/(k + 1))*R(k + 1)*b(k) Some of these transformations have been used to solve the RE. Returns ======= formula : Expr ind : Expr Independent terms. order : int Examples ======== >>> from sympy import exp, ln, S >>> from sympy.series.formal import rsolve_hypergeometric as rh >>> from sympy.abc import x, k >>> rh(exp(x), x, -S.One, (k + 1), k, 1) (Piecewise((1/factorial(k), Eq(Mod(k, 1), 0)), (0, True)), 1, 1) >>> rh(ln(1 + x), x, k**2, k*(k + 1), k, 1) (Piecewise(((-1)**(k - 1)*factorial(k - 1)/RisingFactorial(2, k - 1), Eq(Mod(k, 1), 0)), (0, True)), x, 2) References ========== .. [1] Formal Power Series - Dominik Gruntz, Wolfram Koepf .. [2] Power Series in Computer Algebra - Wolfram Koepf """ result = _rsolve_hypergeometric(f, x, P, Q, k, m) if result is None: return None sol_list, ind, mp = result sol_dict = defaultdict(lambda: S.Zero) for res, cond in sol_list: j, mk = cond.as_coeff_Add() c = mk.coeff(k) if j.is_integer is False: res *= x**frac(j) j = floor(j) res = res.subs(k, (k - j) / c) cond = Eq(k % c, j % c) sol_dict[cond] += res # Group together formula for same conditions sol = [] for cond, res in sol_dict.items(): sol.append((res, cond)) sol.append((S.Zero, True)) sol = Piecewise(*sol) if mp is -oo: s = S.Zero elif mp.is_integer is False: s = ceiling(mp) else: s = mp + 1 # save all the terms of # form 1/x**k in ind if s < 0: ind += sum(sequence(sol * x**k, (k, s, -1))) s = S.Zero return (sol, ind, s)
def _eval_rewrite_as_Piecewise(self, arg): if arg.is_real: return Piecewise((arg, arg >= 0), (-arg, True))
def _eval_rewrite_as_Piecewise(self, arg, **kwargs): if arg.is_extended_real: return Piecewise((arg, arg >= 0), (-arg, True))
def test_Piecewise(): assert refine(Piecewise((1, x < 0), (3, True)), Q.is_true(x < 0)) == 1 assert refine(Piecewise((1, x < 0), (3, True)), ~Q.is_true(x < 0)) == 3 assert refine(Piecewise((1, x < 0), (3, True)), Q.is_true(y < 0)) == Piecewise((1, x < 0), (3, True)) assert refine(Piecewise((1, x > 0), (3, True)), Q.is_true(x > 0)) == 1 assert refine(Piecewise((1, x > 0), (3, True)), ~Q.is_true(x > 0)) == 3 assert refine(Piecewise((1, x > 0), (3, True)), Q.is_true(y > 0)) == Piecewise((1, x > 0), (3, True)) assert refine(Piecewise((1, x <= 0), (3, True)), Q.is_true(x <= 0)) == 1 assert refine(Piecewise((1, x <= 0), (3, True)), ~Q.is_true(x <= 0)) == 3 assert refine(Piecewise((1, x <= 0), (3, True)), Q.is_true(y <= 0)) == Piecewise((1, x <= 0), (3, True)) assert refine(Piecewise((1, x >= 0), (3, True)), Q.is_true(x >= 0)) == 1 assert refine(Piecewise((1, x >= 0), (3, True)), ~Q.is_true(x >= 0)) == 3 assert refine(Piecewise((1, x >= 0), (3, True)), Q.is_true(y >= 0)) == Piecewise((1, x >= 0), (3, True)) assert refine(Piecewise((1, Eq(x, 0)), (3, True)), Q.is_true(Eq(x, 0))) == 1 assert refine(Piecewise((1, Eq(x, 0)), (3, True)), Q.is_true(Eq(0, x))) == 1 assert refine(Piecewise((1, Eq(x, 0)), (3, True)), ~Q.is_true(Eq(x, 0))) == 3 assert refine(Piecewise((1, Eq(x, 0)), (3, True)), ~Q.is_true(Eq(0, x))) == 3 assert refine(Piecewise((1, Eq(x, 0)), (3, True)), Q.is_true(Eq(y, 0))) == Piecewise((1, Eq(x, 0)), (3, True)) assert refine(Piecewise((1, Ne(x, 0)), (3, True)), Q.is_true(Ne(x, 0))) == 1 assert refine(Piecewise((1, Ne(x, 0)), (3, True)), ~Q.is_true(Ne(x, 0))) == 3 assert refine(Piecewise((1, Ne(x, 0)), (3, True)), Q.is_true(Ne(y, 0))) == Piecewise((1, Ne(x, 0)), (3, True))
def test_integrate_Piecewise_rational_over_reals(): f = Piecewise((0, t - 478.515625 * pi < 0), (13.2075145209219 * pi / (0.000871222 * t + 0.995)**2, t - 478.515625 * pi >= 0)) assert abs((integrate(f, (t, 0, oo)) - 15235.9375 * pi).evalf()) <= 1e-7
def test_issue_12251(): assert manualintegrate(x**y, x) == Piecewise( (x**(y + 1) / (y + 1), Ne(y, -1)), (log(x), True))
def pmf(self, x): if isinstance(self.succ, Symbol) and isinstance(self.fail, Symbol): return Piecewise((self.p, x == self.succ), (1 - self.p, x == self.fail), (S.Zero, True)) return Piecewise((self.p, Eq(x, self.succ)), (1 - self.p, Eq(x, self.fail)), (S.Zero, True))
def eval_sum_symbolic(f, limits): (i, a, b) = limits if not f.has(i): return f * (b - a + 1) # Linearity if f.is_Mul: L, R = f.as_two_terms() if not L.has(i): sR = eval_sum_symbolic(R, (i, a, b)) if sR: return L * sR if not R.has(i): sL = eval_sum_symbolic(L, (i, a, b)) if sL: return R * sL try: f = apart(f, i) # see if it becomes an Add except PolynomialError: pass if f.is_Add: L, R = f.as_two_terms() lrsum = telescopic(L, R, (i, a, b)) if lrsum: return lrsum lsum = eval_sum_symbolic(L, (i, a, b)) rsum = eval_sum_symbolic(R, (i, a, b)) if None not in (lsum, rsum): return lsum + rsum # Polynomial terms with Faulhaber's formula n = Wild('n') result = f.match(i**n) if result is not None: n = result[n] if n.is_Integer: if n >= 0: if (b is S.Infinity and not a is S.NegativeInfinity) or \ (a is S.NegativeInfinity and not b is S.Infinity): return S.Infinity return ((C.bernoulli(n + 1, b + 1) - C.bernoulli(n + 1, a)) / (n + 1)).expand() elif a.is_Integer and a >= 1: if n == -1: return C.harmonic(b) - C.harmonic(a - 1) else: return C.harmonic(b, abs(n)) - C.harmonic(a - 1, abs(n)) if not (a.has(S.Infinity, S.NegativeInfinity) or b.has(S.Infinity, S.NegativeInfinity)): # Geometric terms c1 = C.Wild('c1', exclude=[i]) c2 = C.Wild('c2', exclude=[i]) c3 = C.Wild('c3', exclude=[i]) e = f.match(c1**(c2 * i + c3)) if e is not None: p = (c1**c3).subs(e) q = (c1**c2).subs(e) r = p * (q**a - q**(b + 1)) / (1 - q) l = p * (b - a + 1) return Piecewise((l, Eq(q, S.One)), (r, True)) r = gosper_sum(f, (i, a, b)) if not r in (None, S.NaN): return r return eval_sum_hyper(f, (i, a, b))
def test_rewrite(): x, y = Symbol('x', real=True), Symbol('y') assert Heaviside(x).rewrite(Piecewise) == (Piecewise( (0, x < 0), (Heaviside(0), Eq(x, 0)), (1, x > 0))) assert Heaviside(y).rewrite(Piecewise) == (Piecewise( (0, y < 0), (Heaviside(0), Eq(y, 0)), (1, y > 0))) assert Heaviside(x, y).rewrite(Piecewise) == (Piecewise( (0, x < 0), (y, Eq(x, 0)), (1, x > 0))) assert Heaviside(x, 0).rewrite(Piecewise) == (Piecewise((0, x <= 0), (1, x > 0))) assert Heaviside(x, 1).rewrite(Piecewise) == (Piecewise((0, x < 0), (1, x >= 0))) assert Heaviside(x, nan).rewrite(Piecewise) == (Piecewise( (0, x < 0), (nan, Eq(x, 0)), (1, x > 0))) assert Heaviside(x).rewrite(sign) == \ Heaviside(x, H0=Heaviside(0)).rewrite(sign) == \ Piecewise( (sign(x)/2 + S(1)/2, Eq(Heaviside(0), S(1)/2)), (Piecewise( (sign(x)/2 + S(1)/2, Ne(x, 0)), (Heaviside(0), True)), True) ) assert Heaviside(y).rewrite(sign) == Heaviside(y) assert Heaviside(x, S.Half).rewrite(sign) == (sign(x) + 1) / 2 assert Heaviside(x, y).rewrite(sign) == \ Piecewise( (sign(x)/2 + S(1)/2, Eq(y, S(1)/2)), (Piecewise( (sign(x)/2 + S(1)/2, Ne(x, 0)), (y, True)), True) ) assert DiracDelta(y).rewrite(Piecewise) == Piecewise( (DiracDelta(0), Eq(y, 0)), (0, True)) assert DiracDelta(y, 1).rewrite(Piecewise) == DiracDelta(y, 1) assert DiracDelta(x - 5).rewrite(Piecewise) == (Piecewise( (DiracDelta(0), Eq(x - 5, 0)), (0, True))) assert (x * DiracDelta(x - 10)).rewrite( SingularityFunction) == x * SingularityFunction(x, 10, -1) assert 5 * x * y * DiracDelta( y, 1).rewrite(SingularityFunction) == 5 * x * y * SingularityFunction( y, 0, -2) assert DiracDelta(0).rewrite(SingularityFunction) == SingularityFunction( 0, 0, -1) assert DiracDelta(0, 1).rewrite(SingularityFunction) == SingularityFunction( 0, 0, -2) assert Heaviside(x).rewrite(SingularityFunction) == SingularityFunction( x, 0, 0) assert 5 * x * y * Heaviside(y + 1).rewrite( SingularityFunction) == 5 * x * y * SingularityFunction(y, -1, 0) assert ((x - 3)**3 * Heaviside(x - 3)).rewrite( SingularityFunction) == (x - 3)**3 * SingularityFunction(x, 3, 0) assert Heaviside(0).rewrite(SingularityFunction) == S.Half
def test_periodicity(): x = Symbol('x') y = Symbol('y') z = Symbol('z', real=True) assert periodicity(sin(2 * x), x) == pi assert periodicity((-2) * tan(4 * x), x) == pi / 4 assert periodicity(sin(x)**2, x) == 2 * pi assert periodicity(3**tan(3 * x), x) == pi / 3 assert periodicity(tan(x) * cos(x), x) == 2 * pi assert periodicity(sin(x)**(tan(x)), x) == 2 * pi assert periodicity(tan(x) * sec(x), x) == 2 * pi assert periodicity(sin(2 * x) * cos(2 * x) - y, x) == pi / 2 assert periodicity(tan(x) + cot(x), x) == pi assert periodicity(sin(x) - cos(2 * x), x) == 2 * pi assert periodicity(sin(x) - 1, x) == 2 * pi assert periodicity(sin(4 * x) + sin(x) * cos(x), x) == pi assert periodicity(exp(sin(x)), x) == 2 * pi assert periodicity(log(cot(2 * x)) - sin(cos(2 * x)), x) == pi assert periodicity(sin(2 * x) * exp(tan(x) - csc(2 * x)), x) == pi assert periodicity(cos(sec(x) - csc(2 * x)), x) == 2 * pi assert periodicity(tan(sin(2 * x)), x) == pi assert periodicity(2 * tan(x)**2, x) == pi assert periodicity(sin(x % 4), x) == 4 assert periodicity(sin(x) % 4, x) == 2 * pi assert periodicity(tan((3 * x - 2) % 4), x) == Rational(4, 3) assert periodicity((sqrt(2) * (x + 1) + x) % 3, x) == 3 / (sqrt(2) + 1) assert periodicity((x**2 + 1) % x, x) is None assert periodicity(sin(re(x)), x) == 2 * pi assert periodicity(sin(x)**2 + cos(x)**2, x) is S.Zero assert periodicity(tan(x), y) is S.Zero assert periodicity(sin(x) + I * cos(x), x) == 2 * pi assert periodicity(x - sin(2 * y), y) == pi assert periodicity(exp(x), x) is None assert periodicity(exp(I * x), x) == 2 * pi assert periodicity(exp(I * z), z) == 2 * pi assert periodicity(exp(z), z) is None assert periodicity(exp(log(sin(z) + I * cos(2 * z)), evaluate=False), z) == 2 * pi assert periodicity(exp(log(sin(2 * z) + I * cos(z)), evaluate=False), z) == 2 * pi assert periodicity(exp(sin(z)), z) == 2 * pi assert periodicity(exp(2 * I * z), z) == pi assert periodicity(exp(z + I * sin(z)), z) is None assert periodicity(exp(cos(z / 2) + sin(z)), z) == 4 * pi assert periodicity(log(x), x) is None assert periodicity(exp(x)**sin(x), x) is None assert periodicity(sin(x)**y, y) is None assert periodicity(Abs(sin(Abs(sin(x)))), x) == pi assert all( periodicity(Abs(f(x)), x) == pi for f in (cos, sin, sec, csc, tan, cot)) assert periodicity(Abs(sin(tan(x))), x) == pi assert periodicity(Abs(sin(sin(x) + tan(x))), x) == 2 * pi assert periodicity(sin(x) > S.Half, x) == 2 * pi assert periodicity(x > 2, x) is None assert periodicity(x**3 - x**2 + 1, x) is None assert periodicity(Abs(x), x) is None assert periodicity(Abs(x**2 - 1), x) is None assert periodicity((x**2 + 4) % 2, x) is None assert periodicity((E**x) % 3, x) is None assert periodicity(sin(expint(1, x)) / expint(1, x), x) is None # returning `None` for any Piecewise p = Piecewise((0, x < -1), (x**2, x <= 1), (log(x), True)) assert periodicity(p, x) is None m = MatrixSymbol('m', 3, 3) raises(NotImplementedError, lambda: periodicity(sin(m), m)) raises(NotImplementedError, lambda: periodicity(sin(m[0, 0]), m)) raises(NotImplementedError, lambda: periodicity(sin(m), m[0, 0])) raises(NotImplementedError, lambda: periodicity(sin(m[0, 0]), m[0, 0]))
def test_BernoulliProcess(): B = BernoulliProcess("B", p=0.6, success=1, failure=0) assert B.state_space == FiniteSet(0, 1) assert B.index_set == S.Naturals0 assert B.success == 1 assert B.failure == 0 X = BernoulliProcess("X", p=Rational(1, 3), success='H', failure='T') assert X.state_space == FiniteSet('H', 'T') H, T = symbols("H,T") assert E(X[1] + X[2] * X[3] ) == H**2 / 9 + 4 * H * T / 9 + H / 3 + 4 * T**2 / 9 + 2 * T / 3 t, x = symbols('t, x', positive=True, integer=True) assert isinstance(B[t], RandomIndexedSymbol) raises(ValueError, lambda: BernoulliProcess("X", p=1.1, success=1, failure=0)) raises(NotImplementedError, lambda: B(t)) raises(IndexError, lambda: B[-3]) assert B.joint_distribution(B[3], B[9]) == JointDistributionHandmade( Lambda( (B[3], B[9]), Piecewise((0.6, Eq(B[3], 1)), (0.4, Eq(B[3], 0)), (0, True)) * Piecewise((0.6, Eq(B[9], 1)), (0.4, Eq(B[9], 0)), (0, True)))) assert B.joint_distribution(2, B[4]) == JointDistributionHandmade( Lambda( (B[2], B[4]), Piecewise((0.6, Eq(B[2], 1)), (0.4, Eq(B[2], 0)), (0, True)) * Piecewise((0.6, Eq(B[4], 1)), (0.4, Eq(B[4], 0)), (0, True)))) # Test for the sum distribution of Bernoulli Process RVs Y = B[1] + B[2] + B[3] assert P(Eq(Y, 0)).round(2) == Float(0.06, 1) assert P(Eq(Y, 2)).round(2) == Float(0.43, 2) assert P(Eq(Y, 4)).round(2) == 0 assert P(Gt(Y, 1)).round(2) == Float(0.65, 2) # Test for independency of each Random Indexed variable assert P(Eq(B[1], 0) & Eq(B[2], 1) & Eq(B[3], 0) & Eq(B[4], 1)).round(2) == Float(0.06, 1) assert E(2 * B[1] + B[2]).round(2) == Float(1.80, 3) assert E(2 * B[1] + B[2] + 5).round(2) == Float(6.80, 3) assert E(B[2] * B[4] + B[10]).round(2) == Float(0.96, 2) assert E(B[2] > 0, Eq(B[1], 1) & Eq(B[2], 1)).round(2) == Float(0.60, 2) assert E(B[1]) == 0.6 assert P(B[1] > 0).round(2) == Float(0.60, 2) assert P(B[1] < 1).round(2) == Float(0.40, 2) assert P(B[1] > 0, B[2] <= 1).round(2) == Float(0.60, 2) assert P(B[12] * B[5] > 0).round(2) == Float(0.36, 2) assert P(B[12] * B[5] > 0, B[4] < 1).round(2) == Float(0.36, 2) assert P(Eq(B[2], 1), B[2] > 0) == 1 assert P(Eq(B[5], 3)) == 0 assert P(Eq(B[1], 1), B[1] < 0) == 0 assert P(B[2] > 0, Eq(B[2], 1)) == 1 assert P(B[2] < 0, Eq(B[2], 1)) == 0 assert P(B[2] > 0, B[2] == 7) == 0 assert P(B[5] > 0, B[5]) == BernoulliDistribution(0.6, 0, 1) raises(ValueError, lambda: P(3)) raises(ValueError, lambda: P(B[3] > 0, 3)) # test issue 19456 expr = Sum(B[t], (t, 0, 4)) expr2 = Sum(B[t], (t, 1, 3)) expr3 = Sum(B[t]**2, (t, 1, 3)) assert expr.doit() == B[0] + B[1] + B[2] + B[3] + B[4] assert expr2.doit() == Y assert expr3.doit() == B[1]**2 + B[2]**2 + B[3]**2 assert B[2 * t].free_symbols == {B[2 * t], t} assert B[4].free_symbols == {B[4]} assert B[x * t].free_symbols == {B[x * t], x, t} #test issue 20078 assert (2 * B[t] + 3 * B[t]).simplify() == 5 * B[t] assert (2 * B[t] - 3 * B[t]).simplify() == -B[t] assert (2 * (0.25 * B[t])).simplify() == 0.5 * B[t] assert (2 * B[t] * 0.25 * B[t]).simplify() == 0.5 * B[t]**2 assert (B[t]**2 + B[t]**3).simplify() == (B[t] + 1) * B[t]**2
def _eval_rewrite_as_Piecewise(self, *args, **kwargs): from sympy.functions.elementary.piecewise import Piecewise i, j = args return Piecewise((0, Ne(i, j)), (1, True))
def test_isolve_Sets(): n = Dummy('n') assert isolve(Abs(x) <= n, x, relational=False) == \ Piecewise((S.EmptySet, n < 0), (Interval(-n, n), True))
def test_sign(): assert sign(1.2) == 1 assert sign(-1.2) == -1 assert sign(3 * I) == I assert sign(-3 * I) == -I assert sign(0) == 0 assert sign(0, evaluate=False).doit() == 0 assert sign(oo, evaluate=False).doit() == 1 assert sign(nan) is nan assert sign(2 + 2 * I).doit() == sqrt(2) * (2 + 2 * I) / 4 assert sign(2 + 3 * I).simplify() == sign(2 + 3 * I) assert sign(2 + 2 * I).simplify() == sign(1 + I) assert sign(im(sqrt(1 - sqrt(3)))) == 1 assert sign(sqrt(1 - sqrt(3))) == I x = Symbol('x') assert sign(x).is_finite is True assert sign(x).is_complex is True assert sign(x).is_imaginary is None assert sign(x).is_integer is None assert sign(x).is_real is None assert sign(x).is_zero is None assert sign(x).doit() == sign(x) assert sign(1.2 * x) == sign(x) assert sign(2 * x) == sign(x) assert sign(I * x) == I * sign(x) assert sign(-2 * I * x) == -I * sign(x) assert sign(conjugate(x)) == conjugate(sign(x)) p = Symbol('p', positive=True) n = Symbol('n', negative=True) m = Symbol('m', negative=True) assert sign(2 * p * x) == sign(x) assert sign(n * x) == -sign(x) assert sign(n * m * x) == sign(x) x = Symbol('x', imaginary=True) assert sign(x).is_imaginary is True assert sign(x).is_integer is False assert sign(x).is_real is False assert sign(x).is_zero is False assert sign(x).diff(x) == 2 * DiracDelta(-I * x) assert sign(x).doit() == x / Abs(x) assert conjugate(sign(x)) == -sign(x) x = Symbol('x', real=True) assert sign(x).is_imaginary is False assert sign(x).is_integer is True assert sign(x).is_real is True assert sign(x).is_zero is None assert sign(x).diff(x) == 2 * DiracDelta(x) assert sign(x).doit() == sign(x) assert conjugate(sign(x)) == sign(x) x = Symbol('x', nonzero=True) assert sign(x).is_imaginary is False assert sign(x).is_integer is True assert sign(x).is_real is True assert sign(x).is_zero is False assert sign(x).doit() == x / Abs(x) assert sign(Abs(x)) == 1 assert Abs(sign(x)) == 1 x = Symbol('x', positive=True) assert sign(x).is_imaginary is False assert sign(x).is_integer is True assert sign(x).is_real is True assert sign(x).is_zero is False assert sign(x).doit() == x / Abs(x) assert sign(Abs(x)) == 1 assert Abs(sign(x)) == 1 x = 0 assert sign(x).is_imaginary is False assert sign(x).is_integer is True assert sign(x).is_real is True assert sign(x).is_zero is True assert sign(x).doit() == 0 assert sign(Abs(x)) == 0 assert Abs(sign(x)) == 0 nz = Symbol('nz', nonzero=True, integer=True) assert sign(nz).is_imaginary is False assert sign(nz).is_integer is True assert sign(nz).is_real is True assert sign(nz).is_zero is False assert sign(nz)**2 == 1 assert (sign(nz)**3).args == (sign(nz), 3) assert sign(Symbol('x', nonnegative=True)).is_nonnegative assert sign(Symbol('x', nonnegative=True)).is_nonpositive is None assert sign(Symbol('x', nonpositive=True)).is_nonnegative is None assert sign(Symbol('x', nonpositive=True)).is_nonpositive assert sign(Symbol('x', real=True)).is_nonnegative is None assert sign(Symbol('x', real=True)).is_nonpositive is None assert sign(Symbol('x', real=True, zero=False)).is_nonpositive is None x, y = Symbol('x', real=True), Symbol('y') f = Function('f') assert sign(x).rewrite(Piecewise) == \ Piecewise((1, x > 0), (-1, x < 0), (0, True)) assert sign(y).rewrite(Piecewise) == sign(y) assert sign(x).rewrite(Heaviside) == 2 * Heaviside(x, H0=S(1) / 2) - 1 assert sign(y).rewrite(Heaviside) == sign(y) assert sign(y).rewrite(Abs) == Piecewise((0, Eq(y, 0)), (y / Abs(y), True)) assert sign(f(y)).rewrite(Abs) == Piecewise((0, Eq(f(y), 0)), (f(y) / Abs(f(y)), True)) # evaluate what can be evaluated assert sign(exp_polar(I * pi) * pi) is S.NegativeOne eq = -sqrt(10 + 6 * sqrt(3)) + sqrt(1 + sqrt(3)) + sqrt(3 + 3 * sqrt(3)) # if there is a fast way to know when and when you cannot prove an # expression like this is zero then the equality to zero is ok assert sign(eq).func is sign or sign(eq) == 0 # but sometimes it's hard to do this so it's better not to load # abs down with tests that will be very slow q = 1 + sqrt(2) - 2 * sqrt(3) + 1331 * sqrt(6) p = expand(q**3)**Rational(1, 3) d = p - q assert sign(d).func is sign or sign(d) == 0
def test_manualintegrate_rational(): assert manualintegrate(1 / (4 - x**2), x) == Piecewise( (acoth(x / 2) / 2, x**2 > 4), (atanh(x / 2) / 2, x**2 < 4)) assert manualintegrate(1 / (-1 + x**2), x) == Piecewise( (-acoth(x), x**2 > 1), (-atanh(x), x**2 < 1))
def high(self): return Piecewise((self.n, Lt(self.n, self.m) != False), (self.m, True))
def heurisch_wrapper(f, x, rewrite=False, hints=None, mappings=None, retries=3, degree_offset=0, unnecessary_permutations=None): """ A wrapper around the heurisch integration algorithm. This method takes the result from heurisch and checks for poles in the denominator. For each of these poles, the integral is reevaluated, and the final integration result is given in terms of a Piecewise. Examples ======== >>> from sympy.core import symbols >>> from sympy.functions import cos >>> from sympy.integrals.heurisch import heurisch, heurisch_wrapper >>> n, x = symbols('n x') >>> heurisch(cos(n*x), x) sin(n*x)/n >>> heurisch_wrapper(cos(n*x), x) Piecewise((x, Eq(n, 0)), (sin(n*x)/n, True)) See Also ======== heurisch """ from sympy.solvers.solvers import solve, denoms f = sympify(f) if x not in f.free_symbols: return f*x res = heurisch(f, x, rewrite, hints, mappings, retries, degree_offset, unnecessary_permutations) if not isinstance(res, Basic): return res # We consider each denominator in the expression, and try to find # cases where one or more symbolic denominator might be zero. The # conditions for these cases are stored in the list slns. slns = [] for d in denoms(res): try: slns += solve(d, dict=True, exclude=(x,)) except NotImplementedError: pass if not slns: return res slns = list(uniq(slns)) # Remove the solutions corresponding to poles in the original expression. slns0 = [] for d in denoms(f): try: slns0 += solve(d, dict=True, exclude=(x,)) except NotImplementedError: pass slns = [s for s in slns if s not in slns0] if not slns: return res if len(slns) > 1: eqs = [] for sub_dict in slns: eqs.extend([Eq(key, value) for key, value in sub_dict.items()]) slns = solve(eqs, dict=True, exclude=(x,)) + slns # For each case listed in the list slns, we reevaluate the integral. pairs = [] for sub_dict in slns: expr = heurisch(f.subs(sub_dict), x, rewrite, hints, mappings, retries, degree_offset, unnecessary_permutations) cond = And(*[Eq(key, value) for key, value in sub_dict.items()]) pairs.append((expr, cond)) pairs.append((heurisch(f, x, rewrite, hints, mappings, retries, degree_offset, unnecessary_permutations), True)) return Piecewise(*pairs)
def low(self): return Piecewise((0, Gt(0, self.n + self.m - self.N) != False), (self.n + self.m - self.N, True))
def _eval_rewrite_as_Piecewise(self, *args, **kwargs): i, j = args return Piecewise((0, Ne(i, j)), (1, True))
def pmf(self): k = Dummy('k') return Lambda( k, Piecewise((S.Half, Or(Eq(k, -1), Eq(k, 1))), (S.Zero, True)))
def _eval_rewrite_as_Piecewise(self, arg, **kwargs): if arg.is_extended_real: return Piecewise((1, arg > 0), (-1, arg < 0), (0, True))
def pmf(self, x): x = Symbol('x') return Lambda( x, Piecewise(*([(v, Eq(k, x)) for k, v in self.dict.items()] + [(S.Zero, True)])))
def _eval_rewrite_as_Piecewise(self, arg): if arg.is_real: return Piecewise((1, arg > 0), (-1, arg < 0), (0, True))
def eval_sum_symbolic(f, limits): from sympy.functions import harmonic, bernoulli f_orig = f (i, a, b) = limits if not f.has(i): return f * (b - a + 1) # Linearity if f.is_Mul: L, R = f.as_two_terms() if not L.has(i): sR = eval_sum_symbolic(R, (i, a, b)) if sR: return L * sR if not R.has(i): sL = eval_sum_symbolic(L, (i, a, b)) if sL: return R * sL try: f = apart(f, i) # see if it becomes an Add except PolynomialError: pass if f.is_Add: L, R = f.as_two_terms() lrsum = telescopic(L, R, (i, a, b)) if lrsum: return lrsum lsum = eval_sum_symbolic(L, (i, a, b)) rsum = eval_sum_symbolic(R, (i, a, b)) if None not in (lsum, rsum): r = lsum + rsum if not r is S.NaN: return r # Polynomial terms with Faulhaber's formula n = Wild('n') result = f.match(i**n) if result is not None: n = result[n] if n.is_Integer: if n >= 0: if (b is S.Infinity and not a is S.NegativeInfinity) or \ (a is S.NegativeInfinity and not b is S.Infinity): return S.Infinity return ((bernoulli(n + 1, b + 1) - bernoulli(n + 1, a)) / (n + 1)).expand() elif a.is_Integer and a >= 1: if n == -1: return harmonic(b) - harmonic(a - 1) else: return harmonic(b, abs(n)) - harmonic(a - 1, abs(n)) if not (a.has(S.Infinity, S.NegativeInfinity) or b.has(S.Infinity, S.NegativeInfinity)): # Geometric terms c1 = Wild('c1', exclude=[i]) c2 = Wild('c2', exclude=[i]) c3 = Wild('c3', exclude=[i]) wexp = Wild('wexp') # Here we first attempt powsimp on f for easier matching with the # exponential pattern, and attempt expansion on the exponent for easier # matching with the linear pattern. e = f.powsimp().match(c1**wexp) if e is not None: e_exp = e.pop(wexp).expand().match(c2 * i + c3) if e_exp is not None: e.update(e_exp) if e is not None: p = (c1**c3).subs(e) q = (c1**c2).subs(e) r = p * (q**a - q**(b + 1)) / (1 - q) l = p * (b - a + 1) return Piecewise((l, Eq(q, S.One)), (r, True)) r = gosper_sum(f, (i, a, b)) if isinstance(r, (Mul, Add)): from sympy import ordered, Tuple non_limit = r.free_symbols - Tuple(*limits[1:]).free_symbols den = denom(together(r)) den_sym = non_limit & den.free_symbols args = [] for v in ordered(den_sym): try: s = solve(den, v) m = Eq(v, s[0]) if s else S.false if m != False: args.append((Sum(f_orig.subs(*m.args), limits).doit(), m)) break except NotImplementedError: continue args.append((r, True)) return Piecewise(*args) if not r in (None, S.NaN): return r h = eval_sum_hyper(f_orig, (i, a, b)) if h is not None: return h factored = f_orig.factor() if factored != f_orig: return eval_sum_symbolic(factored, (i, a, b))
def pdf(self, *x): n, p = self.n, self.p term_1 = factorial(n)/Mul.fromiter(factorial(x_k) for x_k in x) term_2 = Mul.fromiter(p_k**x_k for p_k, x_k in zip(p, x)) return Piecewise((term_1 * term_2, Eq(sum(x), n)), (0, True))
def _eval_rewrite_as_Abs(self, arg, **kwargs): return Piecewise((0, Eq(arg, 0)), (arg / Abs(arg), True))
def test_hyperrep(): from sympy.functions.special.hyper import (HyperRep, HyperRep_atanh, HyperRep_power1, HyperRep_power2, HyperRep_log1, HyperRep_asin1, HyperRep_asin2, HyperRep_sqrts1, HyperRep_sqrts2, HyperRep_log2, HyperRep_cosasin, HyperRep_sinasin) # First test the base class works. from sympy.functions.elementary.exponential import exp_polar from sympy.functions.elementary.piecewise import Piecewise a, b, c, d, z = symbols('a b c d z') class myrep(HyperRep): @classmethod def _expr_small(cls, x): return a @classmethod def _expr_small_minus(cls, x): return b @classmethod def _expr_big(cls, x, n): return c*n @classmethod def _expr_big_minus(cls, x, n): return d*n assert myrep(z).rewrite('nonrep') == Piecewise((0, abs(z) > 1), (a, True)) assert myrep(exp_polar(I*pi)*z).rewrite('nonrep') == \ Piecewise((0, abs(z) > 1), (b, True)) assert myrep(exp_polar(2*I*pi)*z).rewrite('nonrep') == \ Piecewise((c, abs(z) > 1), (a, True)) assert myrep(exp_polar(3*I*pi)*z).rewrite('nonrep') == \ Piecewise((d, abs(z) > 1), (b, True)) assert myrep(exp_polar(4*I*pi)*z).rewrite('nonrep') == \ Piecewise((2*c, abs(z) > 1), (a, True)) assert myrep(exp_polar(5*I*pi)*z).rewrite('nonrep') == \ Piecewise((2*d, abs(z) > 1), (b, True)) assert myrep(z).rewrite('nonrepsmall') == a assert myrep(exp_polar(I*pi)*z).rewrite('nonrepsmall') == b def t(func, hyp, z): """ Test that func is a valid representation of hyp. """ # First test that func agrees with hyp for small z if not tn(func.rewrite('nonrepsmall'), hyp, z, a=Rational(-1, 2), b=Rational(-1, 2), c=S.Half, d=S.Half): return False # Next check that the two small representations agree. if not tn( func.rewrite('nonrepsmall').subs( z, exp_polar(I*pi)*z).replace(exp_polar, exp), func.subs(z, exp_polar(I*pi)*z).rewrite('nonrepsmall'), z, a=Rational(-1, 2), b=Rational(-1, 2), c=S.Half, d=S.Half): return False # Next check continuity along exp_polar(I*pi)*t expr = func.subs(z, exp_polar(I*pi)*z).rewrite('nonrep') if abs(expr.subs(z, 1 + 1e-15).n() - expr.subs(z, 1 - 1e-15).n()) > 1e-10: return False # Finally check continuity of the big reps. def dosubs(func, a, b): rv = func.subs(z, exp_polar(a)*z).rewrite('nonrep') return rv.subs(z, exp_polar(b)*z).replace(exp_polar, exp) for n in [0, 1, 2, 3, 4, -1, -2, -3, -4]: expr1 = dosubs(func, 2*I*pi*n, I*pi/2) expr2 = dosubs(func, 2*I*pi*n + I*pi, -I*pi/2) if not tn(expr1, expr2, z): return False expr1 = dosubs(func, 2*I*pi*(n + 1), -I*pi/2) expr2 = dosubs(func, 2*I*pi*n + I*pi, I*pi/2) if not tn(expr1, expr2, z): return False return True # Now test the various representatives. a = Rational(1, 3) assert t(HyperRep_atanh(z), hyper([S.Half, 1], [Rational(3, 2)], z), z) assert t(HyperRep_power1(a, z), hyper([-a], [], z), z) assert t(HyperRep_power2(a, z), hyper([a, a - S.Half], [2*a], z), z) assert t(HyperRep_log1(z), -z*hyper([1, 1], [2], z), z) assert t(HyperRep_asin1(z), hyper([S.Half, S.Half], [Rational(3, 2)], z), z) assert t(HyperRep_asin2(z), hyper([1, 1], [Rational(3, 2)], z), z) assert t(HyperRep_sqrts1(a, z), hyper([-a, S.Half - a], [S.Half], z), z) assert t(HyperRep_sqrts2(a, z), -2*z/(2*a + 1)*hyper([-a - S.Half, -a], [S.Half], z).diff(z), z) assert t(HyperRep_log2(z), -z/4*hyper([Rational(3, 2), 1, 1], [2, 2], z), z) assert t(HyperRep_cosasin(a, z), hyper([-a, a], [S.Half], z), z) assert t(HyperRep_sinasin(a, z), 2*a*z*hyper([1 - a, 1 + a], [Rational(3, 2)], z), z)
def _eval_rewrite_as_Piecewise(self, arg): if arg.is_real: return Piecewise((1, arg > 0), (S(1) / 2, Eq(arg, 0)), (0, True))
def test_manualintegrate_inversetrig(): # atan assert manualintegrate(exp(x) / (1 + exp(2 * x)), x) == atan(exp(x)) assert manualintegrate(1 / (4 + 9 * x**2), x) == atan(3 * x / 2) / 6 assert manualintegrate(1 / (16 + 16 * x**2), x) == atan(x) / 16 assert manualintegrate(1 / (4 + x**2), x) == atan(x / 2) / 2 assert manualintegrate(1 / (1 + 4 * x**2), x) == atan(2 * x) / 2 ra = Symbol('a', real=True) rb = Symbol('b', real=True) assert manualintegrate(1/(ra + rb*x**2), x) == \ Piecewise((atan(x/sqrt(ra/rb))/(rb*sqrt(ra/rb)), ra/rb > 0), (-acoth(x/sqrt(-ra/rb))/(rb*sqrt(-ra/rb)), And(ra/rb < 0, x**2 > -ra/rb)), (-atanh(x/sqrt(-ra/rb))/(rb*sqrt(-ra/rb)), And(ra/rb < 0, x**2 < -ra/rb))) assert manualintegrate(1/(4 + rb*x**2), x) == \ Piecewise((atan(x/(2*sqrt(1/rb)))/(2*rb*sqrt(1/rb)), 4/rb > 0), (-acoth(x/(2*sqrt(-1/rb)))/(2*rb*sqrt(-1/rb)), And(4/rb < 0, x**2 > -4/rb)), (-atanh(x/(2*sqrt(-1/rb)))/(2*rb*sqrt(-1/rb)), And(4/rb < 0, x**2 < -4/rb))) assert manualintegrate(1/(ra + 4*x**2), x) == \ Piecewise((atan(2*x/sqrt(ra))/(2*sqrt(ra)), ra/4 > 0), (-acoth(2*x/sqrt(-ra))/(2*sqrt(-ra)), And(ra/4 < 0, x**2 > -ra/4)), (-atanh(2*x/sqrt(-ra))/(2*sqrt(-ra)), And(ra/4 < 0, x**2 < -ra/4))) assert manualintegrate(1 / (4 + 4 * x**2), x) == atan(x) / 4 assert manualintegrate(1 / (a + b * x**2), x) == atan(x / sqrt(a / b)) / (b * sqrt(a / b)) # asin assert manualintegrate(1 / sqrt(1 - x**2), x) == asin(x) assert manualintegrate(1 / sqrt(4 - 4 * x**2), x) == asin(x) / 2 assert manualintegrate(3 / sqrt(1 - 9 * x**2), x) == asin(3 * x) assert manualintegrate(1 / sqrt(4 - 9 * x**2), x) == asin(x * Rational(3, 2)) / 3 # asinh assert manualintegrate(1/sqrt(x**2 + 1), x) == \ asinh(x) assert manualintegrate(1/sqrt(x**2 + 4), x) == \ asinh(x/2) assert manualintegrate(1/sqrt(4*x**2 + 4), x) == \ asinh(x)/2 assert manualintegrate(1/sqrt(4*x**2 + 1), x) == \ asinh(2*x)/2 assert manualintegrate(1/sqrt(a*x**2 + 1), x) == \ Piecewise((sqrt(-1/a)*asin(x*sqrt(-a)), a < 0), (sqrt(1/a)*asinh(sqrt(a)*x), a > 0)) assert manualintegrate(1/sqrt(a + x**2), x) == \ Piecewise((asinh(x*sqrt(1/a)), a > 0), (acosh(x*sqrt(-1/a)), a < 0)) # acosh assert manualintegrate(1/sqrt(x**2 - 1), x) == \ acosh(x) assert manualintegrate(1/sqrt(x**2 - 4), x) == \ acosh(x/2) assert manualintegrate(1/sqrt(4*x**2 - 4), x) == \ acosh(x)/2 assert manualintegrate(1/sqrt(9*x**2 - 1), x) == \ acosh(3*x)/3 assert manualintegrate(1/sqrt(a*x**2 - 4), x) == \ Piecewise((sqrt(1/a)*acosh(sqrt(a)*x/2), a > 0)) assert manualintegrate(1/sqrt(-a + 4*x**2), x) == \ Piecewise((asinh(2*x*sqrt(-1/a))/2, -a > 0), (acosh(2*x*sqrt(1/a))/2, -a < 0)) # From https://www.wikiwand.com/en/List_of_integrals_of_inverse_trigonometric_functions # asin assert manualintegrate(asin(x), x) == x * asin(x) + sqrt(1 - x**2) assert manualintegrate(asin(a * x), x) == Piecewise( ((a * x * asin(a * x) + sqrt(-a**2 * x**2 + 1)) / a, Ne(a, 0)), (0, True)) assert manualintegrate(x * asin(a * x), x) == -a * Integral( x**2 / sqrt(-a**2 * x**2 + 1), x) / 2 + x**2 * asin(a * x) / 2 # acos assert manualintegrate(acos(x), x) == x * acos(x) - sqrt(1 - x**2) assert manualintegrate(acos(a * x), x) == Piecewise( ((a * x * acos(a * x) - sqrt(-a**2 * x**2 + 1)) / a, Ne(a, 0)), (pi * x / 2, True)) assert manualintegrate(x * acos(a * x), x) == a * Integral( x**2 / sqrt(-a**2 * x**2 + 1), x) / 2 + x**2 * acos(a * x) / 2 # atan assert manualintegrate(atan(x), x) == x * atan(x) - log(x**2 + 1) / 2 assert manualintegrate(atan(a * x), x) == Piecewise( ((a * x * atan(a * x) - log(a**2 * x**2 + 1) / 2) / a, Ne(a, 0)), (0, True)) assert manualintegrate( x * atan(a * x), x) == -a * (x / a**2 - atan(x / sqrt(a**(-2))) / (a**4 * sqrt(a**(-2)))) / 2 + x**2 * atan(a * x) / 2 # acsc assert manualintegrate( acsc(x), x) == x * acsc(x) + Integral(1 / (x * sqrt(1 - 1 / x**2)), x) assert manualintegrate( acsc(a * x), x) == x * acsc(a * x) + Integral(1 / (x * sqrt(1 - 1 / (a**2 * x**2))), x) / a assert manualintegrate(x * acsc(a * x), x) == x**2 * acsc(a * x) / 2 + Integral( 1 / sqrt(1 - 1 / (a**2 * x**2)), x) / (2 * a) # asec assert manualintegrate( asec(x), x) == x * asec(x) - Integral(1 / (x * sqrt(1 - 1 / x**2)), x) assert manualintegrate( asec(a * x), x) == x * asec(a * x) - Integral(1 / (x * sqrt(1 - 1 / (a**2 * x**2))), x) / a assert manualintegrate(x * asec(a * x), x) == x**2 * asec(a * x) / 2 - Integral( 1 / sqrt(1 - 1 / (a**2 * x**2)), x) / (2 * a) # acot assert manualintegrate(acot(x), x) == x * acot(x) + log(x**2 + 1) / 2 assert manualintegrate(acot(a * x), x) == Piecewise( ((a * x * acot(a * x) + log(a**2 * x**2 + 1) / 2) / a, Ne(a, 0)), (pi * x / 2, True)) assert manualintegrate( x * acot(a * x), x) == a * (x / a**2 - atan(x / sqrt(a**(-2))) / (a**4 * sqrt(a**(-2)))) / 2 + x**2 * acot(a * x) / 2 # piecewise assert manualintegrate(1/sqrt(a-b*x**2), x) == \ Piecewise((sqrt(a/b)*asin(x*sqrt(b/a))/sqrt(a), And(-b < 0, a > 0)), (sqrt(-a/b)*asinh(x*sqrt(-b/a))/sqrt(a), And(-b > 0, a > 0)), (sqrt(a/b)*acosh(x*sqrt(b/a))/sqrt(-a), And(-b > 0, a < 0))) assert manualintegrate(1/sqrt(a + b*x**2), x) == \ Piecewise((sqrt(-a/b)*asin(x*sqrt(-b/a))/sqrt(a), And(a > 0, b < 0)), (sqrt(a/b)*asinh(x*sqrt(b/a))/sqrt(a), And(a > 0, b > 0)), (sqrt(-a/b)*acosh(x*sqrt(-b/a))/sqrt(-a), And(a < 0, b > 0)))
def test_issue_14238(): # doesn't cause recursion error r = Symbol('r', real=True) assert Abs(r + Piecewise((0, r > 0), (1 - r, True)))