def test_issue_12005(): e1 = Subs(Derivative(f(x), x), x, x) assert e1.diff(x) == Derivative(f(x), x, x) e2 = Subs(Derivative(f(x), x), x, x**2 + 1) assert e2.diff(x) == 2*x*Subs(Derivative(f(x), x, x), x, x**2 + 1) e3 = Subs(Derivative(f(x) + y**2 - y, y), y, y**2) assert e3.diff(y) == 4*y e4 = Subs(Derivative(f(x + y), y), y, (x**2)) assert e4.diff(y) is S.Zero e5 = Subs(Derivative(f(x), x), (y, z), (y, z)) assert e5.diff(x) == Derivative(f(x), x, x) assert f(g(x)).diff(g(x), g(x)) == Derivative(f(g(x)), g(x), g(x))
def test_Subs(): assert Subs(1, (), ()) is S.One # check null subs influence on hashing assert Subs(x, y, z) != Subs(x, y, 1) # neutral subs works assert Subs(x, x, 1).subs(x, y).has(y) # self mapping var/point assert Subs(Derivative(f(x), (x, 2)), x, x).doit() == f(x).diff(x, x) assert Subs(x, x, 0).has(x) # it's a structural answer assert not Subs(x, x, 0).free_symbols assert Subs(Subs(x + y, x, 2), y, 1) == Subs(x + y, (x, y), (2, 1)) assert Subs(x, (x,), (0,)) == Subs(x, x, 0) assert Subs(x, x, 0) == Subs(y, y, 0) assert Subs(x, x, 0).subs(x, 1) == Subs(x, x, 0) assert Subs(y, x, 0).subs(y, 1) == Subs(1, x, 0) assert Subs(f(x), x, 0).doit() == f(0) assert Subs(f(x**2), x**2, 0).doit() == f(0) assert Subs(f(x, y, z), (x, y, z), (0, 1, 1)) != \ Subs(f(x, y, z), (x, y, z), (0, 0, 1)) assert Subs(x, y, 2).subs(x, y).doit() == 2 assert Subs(f(x, y), (x, y, z), (0, 1, 1)) != \ Subs(f(x, y) + z, (x, y, z), (0, 1, 0)) assert Subs(f(x, y), (x, y), (0, 1)).doit() == f(0, 1) assert Subs(Subs(f(x, y), x, 0), y, 1).doit() == f(0, 1) raises(ValueError, lambda: Subs(f(x, y), (x, y), (0, 0, 1))) raises(ValueError, lambda: Subs(f(x, y), (x, x, y), (0, 0, 1))) assert len(Subs(f(x, y), (x, y), (0, 1)).variables) == 2 assert Subs(f(x, y), (x, y), (0, 1)).point == Tuple(0, 1) assert Subs(f(x), x, 0) == Subs(f(y), y, 0) assert Subs(f(x, y), (x, y), (0, 1)) == Subs(f(x, y), (y, x), (1, 0)) assert Subs(f(x)*y, (x, y), (0, 1)) == Subs(f(y)*x, (y, x), (0, 1)) assert Subs(f(x)*y, (x, y), (1, 1)) == Subs(f(y)*x, (x, y), (1, 1)) assert Subs(f(x), x, 0).subs(x, 1).doit() == f(0) assert Subs(f(x), x, y).subs(y, 0) == Subs(f(x), x, 0) assert Subs(y*f(x), x, y).subs(y, 2) == Subs(2*f(x), x, 2) assert (2 * Subs(f(x), x, 0)).subs(Subs(f(x), x, 0), y) == 2*y assert Subs(f(x), x, 0).free_symbols == set() assert Subs(f(x, y), x, z).free_symbols == {y, z} assert Subs(f(x).diff(x), x, 0).doit(), Subs(f(x).diff(x), x, 0) assert Subs(1 + f(x).diff(x), x, 0).doit(), 1 + Subs(f(x).diff(x), x, 0) assert Subs(y*f(x, y).diff(x), (x, y), (0, 2)).doit() == \ 2*Subs(Derivative(f(x, 2), x), x, 0) assert Subs(y**2*f(x), x, 0).diff(y) == 2*y*f(0) e = Subs(y**2*f(x), x, y) assert e.diff(y) == e.doit().diff(y) == y**2*Derivative(f(y), y) + 2*y*f(y) assert Subs(f(x), x, 0) + Subs(f(x), x, 0) == 2*Subs(f(x), x, 0) e1 = Subs(z*f(x), x, 1) e2 = Subs(z*f(y), y, 1) assert e1 + e2 == 2*e1 assert e1.__hash__() == e2.__hash__() assert Subs(z*f(x + 1), x, 1) not in [ e1, e2 ] assert Derivative(f(x), x).subs(x, g(x)) == Derivative(f(g(x)), g(x)) assert Derivative(f(x), x).subs(x, x + y) == Subs(Derivative(f(x), x), x, x + y) assert Subs(f(x)*cos(y) + z, (x, y), (0, pi/3)).n(2) == \ Subs(f(x)*cos(y) + z, (x, y), (0, pi/3)).evalf(2) == \ z + Rational('1/2').n(2)*f(0) assert f(x).diff(x).subs(x, 0).subs(x, y) == f(x).diff(x).subs(x, 0) assert (x*f(x).diff(x).subs(x, 0)).subs(x, y) == y*f(x).diff(x).subs(x, 0) assert Subs(Derivative(g(x)**2, g(x), x), g(x), exp(x) ).doit() == 2*exp(x) assert Subs(Derivative(g(x)**2, g(x), x), g(x), exp(x) ).doit(deep=False) == 2*Derivative(exp(x), x) assert Derivative(f(x, g(x)), x).doit() == Derivative( f(x, g(x)), g(x))*Derivative(g(x), x) + Subs(Derivative( f(y, g(x)), y), y, x)