def _solve_as_poly(f, symbol, solveset_solver, invert_func):
    """
    Solve the equation using polynomial techniques if it already is a
    polynomial equation or, with a change of variables, can be made so.
    """
    result = None
    if f.is_polynomial(symbol):

        solns = roots(f, symbol, cubics=True, quartics=True,
                      quintics=True, domain='EX')
        num_roots = sum(solns.values())
        if degree(f, symbol) <= num_roots:
            result = FiniteSet(*solns.keys())
        else:
            poly = Poly(f, symbol)
            solns = poly.all_roots()
            if poly.degree() <= len(solns):
                result = FiniteSet(*solns)
            else:
                result = ConditionSet(symbol, Eq(f, 0), S.Complexes)
    else:
        poly = Poly(f)
        if poly is None:
            result = ConditionSet(symbol, Eq(f, 0), S.Complexes)
        gens = [g for g in poly.gens if g.has(symbol)]

        if len(gens) == 1:
            poly = Poly(poly, gens[0])
            gen = poly.gen
            deg = poly.degree()
            poly = Poly(poly.as_expr(), poly.gen, composite=True)
            poly_solns = FiniteSet(*roots(poly, cubics=True, quartics=True,
                                          quintics=True).keys())

            if len(poly_solns) < deg:
                result = ConditionSet(symbol, Eq(f, 0), S.Complexes)

            if gen != symbol:
                y = Dummy('y')
                lhs, rhs_s = invert_func(gen, y, symbol)
                if lhs is symbol:
                    result = Union(*[rhs_s.subs(y, s) for s in poly_solns])
                else:
                    result = ConditionSet(symbol, Eq(f, 0), S.Complexes)
        else:
            result = ConditionSet(symbol, Eq(f, 0), S.Complexes)

    if result is not None:
        if isinstance(result, FiniteSet):
            # this is to simplify solutions like -sqrt(-I) to sqrt(2)/2
            # - sqrt(2)*I/2. We are not expanding for solution with free
            # variables because that makes the solution more complicated. For
            # example expand_complex(a) returns re(a) + I*im(a)
            if all([s.free_symbols == set() and not isinstance(s, RootOf)
                    for s in result]):
                s = Dummy('s')
                result = imageset(Lambda(s, expand_complex(s)), result)
        return result
    else:
        return ConditionSet(symbol, Eq(f, 0), S.Complexes)

 def _eval_transpose(self):
     from sympy.functions.elementary.complexes import transpose
     i, p = self.exp.is_integer, self.base.is_complex
     if p:
         return self.base**self.exp
     if i:
         return transpose(self.base)**self.exp
     if i is False and p is False:
         expanded = expand_complex(self)
         if expanded != self:
             return transpose(expanded)

 def _eval_conjugate(self):
     from sympy.functions.elementary.complexes import conjugate as c
     i, p = self.exp.is_integer, self.base.is_positive
     if i:
         return c(self.base)**self.exp
     if p:
         return self.base**c(self.exp)
     if i is False and p is False:
         expanded = expand_complex(self)
         if expanded != self:
             return c(expanded)

 def _eval_adjoint(self):
     from sympy.functions.elementary.complexes import adjoint
     i, p = self.exp.is_integer, self.base.is_positive
     if i:
         return adjoint(self.base)**self.exp
     if p:
         return self.base**adjoint(self.exp)
     if i is False and p is False:
         expanded = expand_complex(self)
         if expanded != self:
             return adjoint(expanded)

    def _intersect(self, other):
        from sympy.solvers.diophantine import diophantine
        if self.base_set is S.Integers:
            g = None
            if isinstance(other, ImageSet) and other.base_set is S.Integers:
                g = other.lamda.expr
                m = other.lamda.variables[0]
            elif other is S.Integers:
                m = g = Dummy('x')
            if g is not None:
                f = self.lamda.expr
                n = self.lamda.variables[0]
                # Diophantine sorts the solutions according to the alphabetic
                # order of the variable names, since the result should not depend
                # on the variable name, they are replaced by the dummy variables
                # below
                a, b = Dummy('a'), Dummy('b')
                f, g = f.subs(n, a), g.subs(m, b)
                solns_set = diophantine(f - g)
                if solns_set == set():
                    return EmptySet()
                solns = list(diophantine(f - g))

                if len(solns) != 1:
                    return

                # since 'a' < 'b', select soln for n
                nsol = solns[0][0]
                t = nsol.free_symbols.pop()
                return imageset(Lambda(n, f.subs(a, nsol.subs(t, n))), S.Integers)

        if other == S.Reals:
            from sympy.solvers.solveset import solveset_real
            from sympy.core.function import expand_complex
            if len(self.lamda.variables) > 1:
                return None

            f = self.lamda.expr
            n = self.lamda.variables[0]

            n_ = Dummy(n.name, real=True)
            f_ = f.subs(n, n_)

            re, im = f_.as_real_imag()
            im = expand_complex(im)

            return imageset(Lambda(n_, re),
                            self.base_set.intersect(
                                solveset_real(im, n_)))

    def _intersect(self, other):
        from sympy import Dummy
        from sympy.solvers.diophantine import diophantine
        from sympy.sets.sets import imageset

        if self.base_set is S.Integers:
            if isinstance(other, ImageSet) and other.base_set is S.Integers:
                f, g = self.lamda.expr, other.lamda.expr
                n, m = self.lamda.variables[0], other.lamda.variables[0]

                # Diophantine sorts the solutions according to the alphabetic
                # order of the variable names, since the result should not depend
                # on the variable name, they are replaced by the dummy variables
                # below
                a, b = Dummy("a"), Dummy("b")
                f, g = f.subs(n, a), g.subs(m, b)
                solns_set = diophantine(f - g)
                if solns_set == set():
                    return EmptySet()
                solns = list(diophantine(f - g))
                if len(solns) == 1:
                    t = list(solns[0][0].free_symbols)[0]
                else:
                    return None

                # since 'a' < 'b'
                return imageset(Lambda(t, f.subs(a, solns[0][0])), S.Integers)

        if other == S.Reals:
            from sympy.solvers.solveset import solveset_real
            from sympy.core.function import expand_complex

            if len(self.lamda.variables) > 1:
                return None

            f = self.lamda.expr
            n = self.lamda.variables[0]

            n_ = Dummy(n.name, real=True)
            f_ = f.subs(n, n_)

            re, im = f_.as_real_imag()
            im = expand_complex(im)

            return imageset(Lambda(n_, re), self.base_set.intersect(solveset_real(im, n_)))

    def _intersect(self, other):
        from sympy.solvers.diophantine import diophantine
        if self.base_set is S.Integers:
            g = None
            if isinstance(other, ImageSet) and other.base_set is S.Integers:
                g = other.lamda.expr
                m = other.lamda.variables[0]
            elif other is S.Integers:
                m = g = Dummy('x')
            if g is not None:
                f = self.lamda.expr
                n = self.lamda.variables[0]
                # Diophantine sorts the solutions according to the alphabetic
                # order of the variable names, since the result should not depend
                # on the variable name, they are replaced by the dummy variables
                # below
                a, b = Dummy('a'), Dummy('b')
                f, g = f.subs(n, a), g.subs(m, b)
                solns_set = diophantine(f - g)
                if solns_set == set():
                    return EmptySet()
                solns = list(diophantine(f - g))

                if len(solns) != 1:
                    return

                # since 'a' < 'b', select soln for n
                nsol = solns[0][0]
                t = nsol.free_symbols.pop()
                return imageset(Lambda(n, f.subs(a, nsol.subs(t, n))), S.Integers)

        if other == S.Reals:
            from sympy.solvers.solveset import solveset_real
            from sympy.core.function import expand_complex
            if len(self.lamda.variables) > 1:
                return None

            f = self.lamda.expr
            n = self.lamda.variables[0]

            n_ = Dummy(n.name, real=True)
            f_ = f.subs(n, n_)

            re, im = f_.as_real_imag()
            im = expand_complex(im)

            return imageset(Lambda(n_, re),
                            self.base_set.intersect(
                                solveset_real(im, n_)))

        elif isinstance(other, Interval):
            from sympy.solvers.solveset import (invert_real, invert_complex,
                                                solveset)

            f = self.lamda.expr
            n = self.lamda.variables[0]
            base_set = self.base_set
            new_inf, new_sup = None, None
            new_lopen, new_ropen = other.left_open, other.right_open

            if f.is_real:
                inverter = invert_real
            else:
                inverter = invert_complex

            g1, h1 = inverter(f, other.inf, n)
            g2, h2 = inverter(f, other.sup, n)

            if all(isinstance(i, FiniteSet) for i in (h1, h2)):
                if g1 == n:
                    if len(h1) == 1:
                        new_inf = h1.args[0]
                if g2 == n:
                    if len(h2) == 1:
                        new_sup = h2.args[0]
                # TODO: Design a technique to handle multiple-inverse
                # functions

                # Any of the new boundary values cannot be determined
                if any(i is None for i in (new_sup, new_inf)):
                    return

                range_set = S.EmptySet

                if all(i.is_real for i in (new_sup, new_inf)):
                    new_interval = Interval(new_inf, new_sup, new_lopen, new_ropen)
                    range_set = base_set._intersect(new_interval)
                else:
                    if other.is_subset(S.Reals):
                        solutions = solveset(f, n, S.Reals)
                        if not isinstance(range_set, (ImageSet, ConditionSet)):
                            range_set = solutions._intersect(other)
                        else:
                            return

                if range_set is S.EmptySet:
                    return S.EmptySet
                elif isinstance(range_set, Range) and range_set.size is not S.Infinity:
                    range_set = FiniteSet(*list(range_set))

#.........这里部分代码省略.........