def as_real_imag(self, deep=True, **hints):
        """
        Returns this function as a complex coordinate.

        Examples
        ========

        >>> from sympy import I
        >>> from sympy.abc import x
        >>> from sympy.functions import log
        >>> log(x).as_real_imag()
        (log(Abs(x)), arg(x))
        >>> log(I).as_real_imag()
        (0, pi/2)
        >>> log(1 + I).as_real_imag()
        (log(sqrt(2)), pi/4)
        >>> log(I*x).as_real_imag()
        (log(Abs(x)), arg(I*x))

        """
        from sympy import Abs, arg
        if deep:
            abs = Abs(self.args[0].expand(deep, **hints))
            arg = arg(self.args[0].expand(deep, **hints))
        else:
            abs = Abs(self.args[0])
            arg = arg(self.args[0])
        if hints.get('log', False):  # Expand the log
            hints['complex'] = False
            return (log(abs).expand(deep, **hints), arg)
        else:
            return (log(abs), arg)

def test_atan2():
    assert atan2.nargs == FiniteSet(2)
    assert atan2(0, 0) == S.NaN
    assert atan2(0, 1) == 0
    assert atan2(1, 1) == pi/4
    assert atan2(1, 0) == pi/2
    assert atan2(1, -1) == 3*pi/4
    assert atan2(0, -1) == pi
    assert atan2(-1, -1) == -3*pi/4
    assert atan2(-1, 0) == -pi/2
    assert atan2(-1, 1) == -pi/4
    i = symbols('i', imaginary=True)
    r = symbols('r', real=True)
    eq = atan2(r, i)
    ans = -I*log((i + I*r)/sqrt(i**2 + r**2))
    reps = ((r, 2), (i, I))
    assert eq.subs(reps) == ans.subs(reps)

    x = Symbol('x', negative=True)
    y = Symbol('y', negative=True)
    assert atan2(y, x) == atan(y/x) - pi
    y = Symbol('y', nonnegative=True)
    assert atan2(y, x) == atan(y/x) + pi
    y = Symbol('y')
    assert atan2(y, x) == atan2(y, x, evaluate=False)

    u = Symbol("u", positive=True)
    assert atan2(0, u) == 0
    u = Symbol("u", negative=True)
    assert atan2(0, u) == pi

    assert atan2(y, oo) ==  0
    assert atan2(y, -oo)==  2*pi*Heaviside(re(y)) - pi

    assert atan2(y, x).rewrite(log) == -I*log((x + I*y)/sqrt(x**2 + y**2))
    assert atan2(y, x).rewrite(atan) == 2*atan(y/(x + sqrt(x**2 + y**2)))

    ex = atan2(y, x) - arg(x + I*y)
    assert ex.subs({x:2, y:3}).rewrite(arg) == 0
    assert ex.subs({x:2, y:3*I}).rewrite(arg) == -pi - I*log(sqrt(5)*I/5)
    assert ex.subs({x:2*I, y:3}).rewrite(arg) == -pi/2 - I*log(sqrt(5)*I)
    assert ex.subs({x:2*I, y:3*I}).rewrite(arg) == -pi + atan(2/S(3)) + atan(3/S(2))
    i = symbols('i', imaginary=True)
    r = symbols('r', real=True)
    e = atan2(i, r)
    rewrite = e.rewrite(arg)
    reps = {i: I, r: -2}
    assert rewrite == -I*log(abs(I*i + r)/sqrt(abs(i**2 + r**2))) + arg((I*i + r)/sqrt(i**2 + r**2))
    assert (e - rewrite).subs(reps).equals(0)

    assert conjugate(atan2(x, y)) == atan2(conjugate(x), conjugate(y))

    assert diff(atan2(y, x), x) == -y/(x**2 + y**2)
    assert diff(atan2(y, x), y) == x/(x**2 + y**2)

    assert simplify(diff(atan2(y, x).rewrite(log), x)) == -y/(x**2 + y**2)
    assert simplify(diff(atan2(y, x).rewrite(log), y)) ==  x/(x**2 + y**2)

def _laplace_transform(f, t, s, simplify=True):
    """ The backend function for laplace transforms. """
    from sympy import (re, Max, exp, pi, Abs, Min, periodic_argument as arg,
                       cos, Wild, symbols)
    F = integrate(exp(-s*t) * f, (t, 0, oo))

    if not F.has(Integral):
        return _simplify(F, simplify), -oo, True

    if not F.is_Piecewise:
        raise IntegralTransformError('Laplace', f, 'could not compute integral')

    F, cond = F.args[0]
    if F.has(Integral):
        raise IntegralTransformError('Laplace', f, 'integral in unexpected form')

    a = -oo
    aux = True
    conds = conjuncts(to_cnf(cond))
    u = Dummy('u', real=True)
    p, q, w1, w2, w3 = symbols('p q w1 w2 w3', cls=Wild, exclude=[s])
    for c in conds:
        a_ = oo
        aux_ = []
        for d in disjuncts(c):
            m = d.match(abs(arg((s + w3)**p*q, w1)) < w2)
            if m:
                if m[q] > 0 and m[w2]/m[p] == pi/2:
                    d = re(s + m[w3]) > 0
            m = d.match(0 < cos(abs(arg(s, q)))*abs(s) - p)
            if m:
                d = re(s) > m[p]
            d_ = d.replace(re, lambda x: x.expand().as_real_imag()[0]).subs(re(s), t)
            if not d.is_Relational or (d.rel_op != '<' and d.rel_op != '<=') \
               or d_.has(s) or not d_.has(t):
                aux_ += [d]
                continue
            soln = _solve_inequality(d_, t)
            if not soln.is_Relational or \
               (soln.rel_op != '<' and soln.rel_op != '<='):
                aux_ += [d]
                continue
            if soln.lhs == t:
                raise IntegralTransformError('Laplace', f,
                                     'convergence not in half-plane?')
            else:
                a_ = Min(soln.lhs, a_)
        if a_ != oo:
            a = Max(a_, a)
        else:
            aux = And(aux, Or(*aux_))

    return _simplify(F, simplify), a, aux

def test_derivatives_issue_4757():
    x = Symbol('x', real=True)
    y = Symbol('y', imaginary=True)
    f = Function('f')
    assert re(f(x)).diff(x) == re(f(x).diff(x))
    assert im(f(x)).diff(x) == im(f(x).diff(x))
    assert re(f(y)).diff(y) == -I*im(f(y).diff(y))
    assert im(f(y)).diff(y) == -I*re(f(y).diff(y))
    assert Abs(f(x)).diff(x).subs(f(x), 1 + I*x).doit() == x/sqrt(1 + x**2)
    assert arg(f(x)).diff(x).subs(f(x), 1 + I*x**2).doit() == 2*x/(1 + x**4)
    assert Abs(f(y)).diff(y).subs(f(y), 1 + y).doit() == -y/sqrt(1 - y**2)
    assert arg(f(y)).diff(y).subs(f(y), I + y**2).doit() == 2*y/(1 + y**4)

def _inverse_mellin_transform(F, s, x_, strip, as_meijerg=False):
    """ A helper for the real inverse_mellin_transform function, this one here
        assumes x to be real and positive. """
    from sympy import (expand, expand_mul, hyperexpand, meijerg, And, Or,
                       arg, pi, re, factor, Heaviside, gamma, Add)
    x = _dummy('t', 'inverse-mellin-transform', F, positive=True)
    # Actually, we won't try integration at all. Instead we use the definition
    # of the Meijer G function as a fairly general inverse mellin transform.
    F = F.rewrite(gamma)
    for g in [factor(F), expand_mul(F), expand(F)]:
        if g.is_Add:
            # do all terms separately
            ress = [_inverse_mellin_transform(G, s, x, strip, as_meijerg,
                                              noconds=False) \
                    for G in g.args]
            conds = [p[1] for p in ress]
            ress = [p[0] for p in ress]
            res = Add(*ress)
            if not as_meijerg:
                res = factor(res, gens=res.atoms(Heaviside))
            return res.subs(x, x_), And(*conds)

        try:
            a, b, C, e, fac = _rewrite_gamma(g, s, strip[0], strip[1])
        except IntegralTransformError:
            continue
        G = meijerg(a, b, C/x**e)
        if as_meijerg:
            h = G
        else:
            h = hyperexpand(G)
            if h.is_Piecewise and len(h.args) == 3:
                # XXX we break modularity here!
                h = Heaviside(x - abs(C))*h.args[0].args[0] \
                  + Heaviside(abs(C) - x)*h.args[1].args[0]
        # We must ensure that the intgral along the line we want converges,
        # and return that value.
        # See [L], 5.2
        cond = [abs(arg(G.argument)) < G.delta*pi]
        # Note: we allow ">=" here, this corresponds to convergence if we let
        # limits go to oo symetrically. ">" corresponds to absolute convergence.
        cond += [And(Or(len(G.ap) != len(G.bq), 0 >= re(G.nu) + 1),
                     abs(arg(G.argument)) == G.delta*pi)]
        cond = Or(*cond)
        if cond is False:
            raise IntegralTransformError('Inverse Mellin', F, 'does not converge')
        return (h*fac).subs(x, x_), cond

    raise IntegralTransformError('Inverse Mellin', F, '')

def test_arg():
    assert arg(0) == nan
    assert arg(1) == 0
    assert arg(-1) == pi
    assert arg(I) == pi/2
    assert arg(-I) == -pi/2
    assert arg(1+I) == pi/4
    assert arg(-1+I) == 3*pi/4
    assert arg(1-I) == -pi/4

    p = Symbol('p', positive=True)
    assert arg(p) == 0

    n = Symbol('n', negative=True)
    assert arg(n) == pi

def test_solve_trig():
    from sympy.abc import n

    assert solveset_real(sin(x), x) == Union(
        imageset(Lambda(n, 2 * pi * n), S.Integers), imageset(Lambda(n, 2 * pi * n + pi), S.Integers)
    )

    assert solveset_real(sin(x) - 1, x) == imageset(Lambda(n, 2 * pi * n + pi / 2), S.Integers)

    assert solveset_real(cos(x), x) == Union(
        imageset(Lambda(n, 2 * pi * n - pi / 2), S.Integers), imageset(Lambda(n, 2 * pi * n + pi / 2), S.Integers)
    )

    assert solveset_real(sin(x) + cos(x), x) == Union(
        imageset(Lambda(n, 2 * n * pi - pi / 4), S.Integers), imageset(Lambda(n, 2 * n * pi + 3 * pi / 4), S.Integers)
    )

    assert solveset_real(sin(x) ** 2 + cos(x) ** 2, x) == S.EmptySet

    assert solveset_complex(cos(x) - S.Half, x) == Union(
        imageset(Lambda(n, 2 * n * pi + pi / 3), S.Integers), imageset(Lambda(n, 2 * n * pi - pi / 3), S.Integers)
    )

    y, a = symbols("y,a")
    assert solveset(sin(y + a) - sin(y), a, domain=S.Reals) == Union(
        imageset(Lambda(n, 2 * n * pi), S.Integers),
        imageset(Lambda(n, -I * (I * (2 * n * pi + arg(-exp(-2 * I * y))) + 2 * im(y))), S.Integers),
    )

def arg(complexe):
    if isinstance(complexe, (int, complex, long, float)):
        return _cmath.log(complexe).imag
    elif isinstance(complexe, _sympy.Basic):
        return _sympy.arg(complexe)
    else:
        return _numpy.imag(_numpy.log(complex))

def polar(z):
    """polar(z) -> r: float, phi: float

    Convert a complex from rectangular coordinates to polar coordinates. r is
    the distance from 0 and phi the phase angle.
    """
    return (Abs(z), arg(z))

def test_derivatives_issue1658():
    x = Symbol('x')
    f = Function('f')
    assert re(f(x)).diff(x) == re(f(x).diff(x))
    assert im(f(x)).diff(x) == im(f(x).diff(x))

    x = Symbol('x', real=True)
    assert Abs(f(x)).diff(x).subs(f(x), 1+I*x).doit() == x/sqrt(1 + x**2)
    assert arg(f(x)).diff(x).subs(f(x), 1+I*x**2).doit() == 2*x/(1+x**4)

def test_meijerint():
    from sympy import symbols, expand, arg

    s, t, mu = symbols("s t mu", real=True)
    assert integrate(
        meijerg([], [], [0], [], s * t) * meijerg([], [], [mu / 2], [-mu / 2], t ** 2 / 4), (t, 0, oo)
    ).is_Piecewise
    s = symbols("s", positive=True)
    assert integrate(x ** s * meijerg([[], []], [[0], []], x), (x, 0, oo)) == gamma(s + 1)
    assert integrate(x ** s * meijerg([[], []], [[0], []], x), (x, 0, oo), meijerg=True) == gamma(s + 1)
    assert isinstance(integrate(x ** s * meijerg([[], []], [[0], []], x), (x, 0, oo), meijerg=False), Integral)

    assert meijerint_indefinite(exp(x), x) == exp(x)

    # TODO what simplifications should be done automatically?
    # This tests "extra case" for antecedents_1.
    a, b = symbols("a b", positive=True)
    assert simplify(meijerint_definite(x ** a, x, 0, b)[0]) == b ** (a + 1) / (a + 1)

    # This tests various conditions and expansions:
    meijerint_definite((x + 1) ** 3 * exp(-x), x, 0, oo) == (16, True)

    # Again, how about simplifications?
    sigma, mu = symbols("sigma mu", positive=True)
    i, c = meijerint_definite(exp(-((x - mu) / (2 * sigma)) ** 2), x, 0, oo)
    assert simplify(i) == sqrt(pi) * sigma * (erf(mu / (2 * sigma)) + 1)
    assert c is True

    i, _ = meijerint_definite(exp(-mu * x) * exp(sigma * x), x, 0, oo)
    # TODO it would be nice to test the condition
    assert simplify(i) == 1 / (mu - sigma)

    # Test substitutions to change limits
    assert meijerint_definite(exp(x), x, -oo, 2) == (exp(2), True)
    assert expand(meijerint_definite(exp(x), x, 0, I)[0]) == exp(I) - 1
    assert expand(meijerint_definite(exp(-x), x, 0, x)[0]) == 1 - exp(-exp(I * arg(x)) * abs(x))

    # Test -oo to oo
    assert meijerint_definite(exp(-x ** 2), x, -oo, oo) == (sqrt(pi), True)
    assert meijerint_definite(exp(-abs(x)), x, -oo, oo) == (2, True)
    assert meijerint_definite(exp(-(2 * x - 3) ** 2), x, -oo, oo) == (sqrt(pi) / 2, True)
    assert meijerint_definite(exp(-abs(2 * x - 3)), x, -oo, oo) == (1, True)
    assert meijerint_definite(exp(-((x - mu) / sigma) ** 2 / 2) / sqrt(2 * pi * sigma ** 2), x, -oo, oo) == (1, True)

    # Test one of the extra conditions for 2 g-functinos
    assert meijerint_definite(exp(-x) * sin(x), x, 0, oo) == (S(1) / 2, True)

    # Test a bug
    def res(n):
        return (1 / (1 + x ** 2)).diff(x, n).subs(x, 1) * (-1) ** n

    for n in range(6):
        assert integrate(exp(-x) * sin(x) * x ** n, (x, 0, oo), meijerg=True) == res(n)

    # Test trigexpand:
    assert integrate(exp(-x) * sin(x + a), (x, 0, oo), meijerg=True) == sin(a) / 2 + cos(a) / 2

def test_invert_complex():
    assert invert_complex(x + 3, y, x) == (x, FiniteSet(y - 3))
    assert invert_complex(x * 3, y, x) == (x, FiniteSet(y / 3))

    assert invert_complex(exp(x), y, x) == (x, imageset(Lambda(n, I * (2 * pi * n + arg(y)) + log(Abs(y))), S.Integers))

    assert invert_complex(log(x), y, x) == (x, FiniteSet(exp(y)))

    raises(ValueError, lambda: invert_real(S.One, y, x))
    raises(ValueError, lambda: invert_complex(x, x, x))

def test_latex_functions():
    assert latex(exp(x)) == "e^{x}"
    assert latex(exp(1)+exp(2)) == "e + e^{2}"

    f = Function('f')
    assert latex(f(x)) == '\\operatorname{f}{\\left (x \\right )}'

    beta = Function('beta')

    assert latex(beta(x)) == r"\beta{\left (x \right )}"
    assert latex(sin(x)) == r"\sin{\left (x \right )}"
    assert latex(sin(x), fold_func_brackets=True) == r"\sin {x}"
    assert latex(sin(2*x**2), fold_func_brackets=True) == \
    r"\sin {2 x^{2}}"
    assert latex(sin(x**2), fold_func_brackets=True) == \
    r"\sin {x^{2}}"

    assert latex(asin(x)**2) == r"\operatorname{asin}^{2}{\left (x \right )}"
    assert latex(asin(x)**2,inv_trig_style="full") == \
        r"\arcsin^{2}{\left (x \right )}"
    assert latex(asin(x)**2,inv_trig_style="power") == \
        r"\sin^{-1}{\left (x \right )}^{2}"
    assert latex(asin(x**2),inv_trig_style="power",fold_func_brackets=True) == \
        r"\sin^{-1} {x^{2}}"

    assert latex(factorial(k)) == r"k!"
    assert latex(factorial(-k)) == r"\left(- k\right)!"

    assert latex(factorial2(k)) == r"k!!"
    assert latex(factorial2(-k)) == r"\left(- k\right)!!"

    assert latex(binomial(2,k)) == r"{\binom{2}{k}}"

    assert latex(FallingFactorial(3,k)) == r"{\left(3\right)}_{\left(k\right)}"
    assert latex(RisingFactorial(3,k)) == r"{\left(3\right)}^{\left(k\right)}"

    assert latex(floor(x)) == r"\lfloor{x}\rfloor"
    assert latex(ceiling(x)) == r"\lceil{x}\rceil"
    assert latex(Abs(x)) == r"\lvert{x}\rvert"
    assert latex(re(x)) == r"\Re{x}"
    assert latex(re(x+y)) == r"\Re {\left (x + y \right )}"
    assert latex(im(x)) == r"\Im{x}"
    assert latex(conjugate(x)) == r"\overline{x}"
    assert latex(gamma(x)) == r"\Gamma\left(x\right)"
    assert latex(Order(x)) == r"\mathcal{O}\left(x\right)"
    assert latex(lowergamma(x, y)) == r'\gamma\left(x, y\right)'
    assert latex(uppergamma(x, y)) == r'\Gamma\left(x, y\right)'

    assert latex(cot(x)) == r'\cot{\left (x \right )}'
    assert latex(coth(x)) == r'\coth{\left (x \right )}'
    assert latex(re(x)) == r'\Re{x}'
    assert latex(im(x)) == r'\Im{x}'
    assert latex(root(x,y)) == r'x^{\frac{1}{y}}'
    assert latex(arg(x)) == r'\arg{\left (x \right )}'
    assert latex(zeta(x)) == r'\zeta{\left (x \right )}'

def test_issue_7173():
    from sympy import cse
    x0, x1, x2, x3 = symbols('x:4')
    ans = laplace_transform(sinh(a*x)*cosh(a*x), x, s)
    r, e = cse(ans)
    assert r == [
        (x0, pi/2),
        (x1, arg(a)),
        (x2, Abs(x1)),
        (x3, Abs(x1 + pi))]
    assert e == [
        a/(-4*a**2 + s**2),
        0,
        ((x0 >= x2) | (x2 < x0)) & ((x0 >= x3) | (x3 < x0))]

 def process_conds(conds):
     """ Turn ``conds`` into a strip and auxiliary conditions. """
     a = -oo
     aux = True
     conds = conjuncts(to_cnf(conds))
     u = Dummy('u', real=True)
     p, q, w1, w2, w3, w4, w5 = symbols('p q w1 w2 w3 w4 w5', cls=Wild, exclude=[s])
     for c in conds:
         a_ = oo
         aux_ = []
         for d in disjuncts(c):
             m = d.match(abs(arg((s + w3)**p*q, w1)) < w2)
             if not m:
                 m = d.match(abs(arg((s + w3)**p*q, w1)) <= w2)
             if not m:
                 m = d.match(abs(arg((polar_lift(s + w3))**p*q, w1)) < w2)
             if not m:
                 m = d.match(abs(arg((polar_lift(s + w3))**p*q, w1)) <= w2)
             if m:
                 if m[q] > 0 and m[w2]/m[p] == pi/2:
                     d = re(s + m[w3]) > 0
             m = d.match(0 < cos(abs(arg(s**w1*w5, q))*w2)*abs(s**w3)**w4 - p)
             if not m:
                 m = d.match(0 < cos(abs(arg(polar_lift(s)**w1*w5, q))*w2)*abs(s**w3)**w4 - p)
             if m and all(m[wild] > 0 for wild in [w1, w2, w3, w4, w5]):
                 d = re(s) > m[p]
             d_ = d.replace(re, lambda x: x.expand().as_real_imag()[0]).subs(re(s), t)
             if not d.is_Relational or \
                d.rel_op not in ('>', '>=', '<', '<=') \
                or d_.has(s) or not d_.has(t):
                 aux_ += [d]
                 continue
             soln = _solve_inequality(d_, t)
             if not soln.is_Relational or \
                soln.rel_op not in ('>', '>=', '<', '<='):
                 aux_ += [d]
                 continue
             if soln.lts == t:
                 raise IntegralTransformError('Laplace', f,
                                      'convergence not in half-plane?')
             else:
                 a_ = Min(soln.lts, a_)
         if a_ != oo:
             a = Max(a_, a)
         else:
             aux = And(aux, Or(*aux_))
     return a, aux

def test_atan2():
    assert atan2.nargs == FiniteSet(2)
    assert atan2(0, 0) == S.NaN
    assert atan2(0, 1) == 0
    assert atan2(1, 1) == pi/4
    assert atan2(1, 0) == pi/2
    assert atan2(1, -1) == 3*pi/4
    assert atan2(0, -1) == pi
    assert atan2(-1, -1) == -3*pi/4
    assert atan2(-1, 0) == -pi/2
    assert atan2(-1, 1) == -pi/4

    u = Symbol("u", positive=True)
    assert atan2(0, u) == 0
    u = Symbol("u", negative=True)
    assert atan2(0, u) == pi

    assert atan2(y, oo) ==  0
    assert atan2(y, -oo)==  2*pi*Heaviside(re(y)) - pi

    assert atan2(y, x).rewrite(log) == -I*log((x + I*y)/sqrt(x**2 + y**2))
    assert atan2(y, x).rewrite(atan) == 2*atan(y/(x + sqrt(x**2 + y**2)))

    ex = atan2(y, x) - arg(x + I*y)
    assert ex.subs({x:2, y:3}).rewrite(arg) == 0
    assert ex.subs({x:2, y:3*I}).rewrite(arg) == 0
    assert ex.subs({x:2*I, y:3}).rewrite(arg) == 0
    assert ex.subs({x:2*I, y:3*I}).rewrite(arg) == 0

    assert conjugate(atan2(x, y)) == atan2(conjugate(x), conjugate(y))

    assert diff(atan2(y, x), x) == -y/(x**2 + y**2)
    assert diff(atan2(y, x), y) == x/(x**2 + y**2)

    assert simplify(diff(atan2(y, x).rewrite(log), x)) == -y/(x**2 + y**2)
    assert simplify(diff(atan2(y, x).rewrite(log), y)) ==  x/(x**2 + y**2)

    assert isinstance(atan2(2, 3*I).n(), atan2)

def test_issue936():
    x = Symbol('x')
    assert Abs(x).expand(trig=True)     == Abs(x)
    assert sign(x).expand(trig=True)    == sign(x)
    assert arg(x).expand(trig=True)     == arg(x)

def test_issue_4035():
    x = Symbol("x")
    assert Abs(x).expand(trig=True) == Abs(x)
    assert sign(x).expand(trig=True) == sign(x)
    assert arg(x).expand(trig=True) == arg(x)

def test_arg_rewrite():
    assert arg(1 + I) == atan2(1, 1)

    x = Symbol('x', real=True)
    y = Symbol('y', real=True)
    assert arg(x + I*y).rewrite(atan2) == atan2(y, x)

def test_arg():
    assert arg(0) == nan
    assert arg(1) == 0
    assert arg(-1) == pi
    assert arg(I) == pi/2
    assert arg(-I) == -pi/2
    assert arg(1 + I) == pi/4
    assert arg(-1 + I) == 3*pi/4
    assert arg(1 - I) == -pi/4
    f = Function('f')
    assert not arg(f(0) + I*f(1)).atoms(re)

    p = Symbol('p', positive=True)
    assert arg(p) == 0

    n = Symbol('n', negative=True)
    assert arg(n) == pi

    x = Symbol('x')
    assert conjugate(arg(x)) == arg(x)

    e = p + I*p**2
    assert arg(e) == arg(1 + p*I)
    # make sure sign doesn't swap
    e = -2*p + 4*I*p**2
    assert arg(e) == arg(-1 + 2*p*I)
    # make sure sign isn't lost
    x = symbols('x', real=True)  # could be zero
    e = x + I*x
    assert arg(e) == arg(x*(1 + I))
    assert arg(e/p) == arg(x*(1 + I))
    e = p*cos(p) + I*log(p)*exp(p)
    assert arg(e).args[0] == e
    # keep it simple -- let the user do more advanced cancellation
    e = (p + 1) + I*(p**2 - 1)
    assert arg(e).args[0] == e

    f = Function('f')
    e = 2*x*(f(0) - 1) - 2*x*f(0)
    assert arg(e) == arg(-2*x)
    assert arg(f(0)).func == arg and arg(f(0)).args == (f(0),)