Python simplify.fraction函数代码示例

def _solve_as_rational(f, symbol, solveset_solver, as_poly_solver):
    """ solve rational functions"""
    f = together(f, deep=True)
    g, h = fraction(f)
    if not h.has(symbol):
        return as_poly_solver(g, symbol)
    else:
        valid_solns = solveset_solver(g, symbol)
        invalid_solns = solveset_solver(h, symbol)
        return valid_solns - invalid_solns

def _solve_as_rational(f, symbol, domain):
    """ solve rational functions"""
    f = together(f, deep=True)
    g, h = fraction(f)
    if not h.has(symbol):
        return _solve_as_poly(g, symbol, domain)
    else:
        valid_solns = _solveset(g, symbol, domain)
        invalid_solns = _solveset(h, symbol, domain)
        return valid_solns - invalid_solns

def _solve_real_trig(f, symbol):
    """ Helper to solve trigonometric equations """
    f = trigsimp(f)
    f = f.rewrite(exp)
    f = together(f)
    g, h = fraction(f)
    y = Dummy('y')
    g, h = g.expand(), h.expand()
    g, h = g.subs(exp(I*symbol), y), h.subs(exp(I*symbol), y)
    if g.has(symbol) or h.has(symbol):
        raise NotImplementedError

    solns = solveset_complex(g, y) - solveset_complex(h, y)

    if isinstance(solns, FiniteSet):
        return Union(*[invert_complex(exp(I*symbol), s, symbol)[1]
                       for s in solns])
    elif solns is S.EmptySet:
        return S.EmptySet
    else:
        raise NotImplementedError

def _solve_trig(f, symbol, domain):
    """ Helper to solve trigonometric equations """
    f = trigsimp(f)
    f_original = f
    f = f.rewrite(exp)
    f = together(f)
    g, h = fraction(f)
    y = Dummy("y")
    g, h = g.expand(), h.expand()
    g, h = g.subs(exp(I * symbol), y), h.subs(exp(I * symbol), y)
    if g.has(symbol) or h.has(symbol):
        return ConditionSet(symbol, Eq(f, 0), S.Reals)

    solns = solveset_complex(g, y) - solveset_complex(h, y)

    if isinstance(solns, FiniteSet):
        result = Union(*[invert_complex(exp(I * symbol), s, symbol)[1] for s in solns])
        return Intersection(result, domain)
    elif solns is S.EmptySet:
        return S.EmptySet
    else:
        return ConditionSet(symbol, Eq(f_original, 0), S.Reals)

def solveset_complex(f, symbol):
    """ Solve a complex valued equation.

    Parameters
    ==========

    f : Expr
        The target equation
    symbol : Symbol
        The variable for which the equation is solved

    Returns
    =======

    Set
        A set of values for `symbol` for which `f` equal to
        zero. An `EmptySet` is returned if no solution is found.

    `solveset_complex` claims to be complete in the solution set that
    it returns.

    Raises
    ======

    NotImplementedError
        The algorithms for to find the solution of the given equation are
        not yet implemented.
    ValueError
        The input is not valid.
    RuntimeError
        It is a bug, please report to the github issue tracker.

    See Also
    ========

    solveset_real: solver for real domain

    Examples
    ========

    >>> from sympy import Symbol, exp
    >>> from sympy.solvers.solveset import solveset_complex
    >>> from sympy.abc import x, a, b, c
    >>> solveset_complex(a*x**2 + b*x +c, x)
    {-b/(2*a) - sqrt(-4*a*c + b**2)/(2*a), -b/(2*a) + sqrt(-4*a*c + b**2)/(2*a)}

    Due to the fact that complex extension of my real valued functions are
    multivariate even some simple equations can have infinitely many solution.

    >>> solveset_complex(exp(x) - 1, x)
    ImageSet(Lambda(_n, 2*_n*I*pi), Integers())

    """
    if not symbol.is_Symbol:
        raise ValueError(" %s is not a symbol" % (symbol))

    f = sympify(f)
    original_eq = f
    if not isinstance(f, (Expr, Number)):
        raise ValueError(" %s is not a valid sympy expression" % (f))

    f = together(f)
    # Without this equations like a + 4*x**2 - E keep oscillating
    # into form  a/4 + x**2 - E/4 and (a + 4*x**2 - E)/4
    if not fraction(f)[1].has(symbol):
        f = expand(f)

    if f.is_zero:
        raise NotImplementedError("S.Complex set is not yet implemented")
    elif not f.has(symbol):
        result = EmptySet()
    elif f.is_Mul and all([_is_finite_with_finite_vars(m) for m in f.args]):
        result = Union(*[solveset_complex(m, symbol) for m in f.args])
    else:
        lhs, rhs_s = invert_complex(f, 0, symbol)
        if lhs == symbol:
            result = rhs_s
        elif isinstance(rhs_s, FiniteSet):
            equations = [lhs - rhs for rhs in rhs_s]
            result = EmptySet()
            for equation in equations:
                if equation == f:
                    result += _solve_as_rational(equation, symbol,
                                                 solveset_solver=solveset_complex,
                                                 as_poly_solver=_solve_as_poly_complex)
                else:
                    result += solveset_complex(equation, symbol)
        else:
            raise NotImplementedError

    if isinstance(result, FiniteSet):
        result = [s for s in result
                  if isinstance(s, RootOf)
                  or domain_check(original_eq, symbol, s)]
        return FiniteSet(*result)
    else:
        return result

def count_ops(expr, visual=False):
    """
    Return a representation (integer or expression) of the operations in expr.

    If `visual` is False (default) then the sum of the coefficients of the
    visual expression will be returned.

    If `visual` is True then the number of each type of operation is shown
    with the core class types (or their virtual equivalent) multiplied by the
    number of times they occur.

    If expr is an iterable, the sum of the op counts of the
    items will be returned.

    Examples:
        >>> from sympy.abc import a, b, x, y
        >>> from sympy import sin, count_ops

    Although there isn't a SUB object, minus signs are interpreted as
    either negations or subtractions:
        >>> (x - y).count_ops(visual=True)
        SUB
        >>> (-x).count_ops(visual=True)
        NEG

    Here, there are two Adds and a Pow:
        >>> (1 + a + b**2).count_ops(visual=True)
        POW + 2*ADD

    In the following, an Add, Mul, Pow and two functions:
        >>> (sin(x)*x + sin(x)**2).count_ops(visual=True)
        ADD + MUL + POW + 2*SIN

    for a total of 5:
        >>> (sin(x)*x + sin(x)**2).count_ops(visual=False)
        5

    Note that "what you type" is not always what you get. The expression
    1/x/y is translated by sympy into 1/(x*y) so it gives a DIV and MUL rather
    than two DIVs:
        >>> (1/x/y).count_ops(visual=True)
        DIV + MUL

    The visual option can be used to demonstrate the difference in
    operations for expressions in different forms. Here, the Horner
    representation is compared with the expanded form of a polynomial:
        >>> eq=x*(1 + x*(2 + x*(3 + x)))
        >>> count_ops(eq.expand(), visual=True) - count_ops(eq, visual=True)
        -MUL + 3*POW

    The count_ops function also handles iterables:
        >>> count_ops([x, sin(x), None, True, x + 2], visual=False)
        2
        >>> count_ops([x, sin(x), None, True, x + 2], visual=True)
        ADD + SIN
        >>> count_ops({x: sin(x), x + 2: y + 1}, visual=True)
        SIN + 2*ADD

    """
    from sympy.simplify.simplify import fraction

    expr = sympify(expr)
    if isinstance(expr, Expr):

        ops = []
        args = [expr]
        NEG = C.Symbol('NEG')
        DIV = C.Symbol('DIV')
        SUB = C.Symbol('SUB')
        ADD = C.Symbol('ADD')
        def isneg(a):
            c = a.as_coeff_mul()[0]
            return c.is_Number and c.is_negative
        while args:
            a = args.pop()
            if a.is_Rational:
                #-1/3 = NEG + DIV
                if a is not S.One:
                    if a.p < 0:
                        ops.append(NEG)
                    if a.q != 1:
                        ops.append(DIV)
                    continue
            elif a.is_Mul:
                if isneg(a):
                    ops.append(NEG)
                    if a.args[0] is S.NegativeOne:
                        a = a.as_two_terms()[1]
                    else:
                        a = -a
                n, d = fraction(a)
                if n.is_Integer:
                    ops.append(DIV)
                    if n < 0:
                        ops.append(NEG)
                    args.append(d)
                    continue # won't be -Mul but could be Add
                elif d is not S.One:
                    if not d.is_Integer:
                        args.append(d)
#.........这里部分代码省略.........

def solveset_real(f, symbol):
    """ Solves a real valued equation.

    Parameters
    ==========

    f : Expr
        The target equation
    symbol : Symbol
        The variable for which the equation is solved

    Returns
    =======

    Set
        A set of values for `symbol` for which `f` is equal to
        zero. An `EmptySet` is returned if no solution is found.
        A `ConditionSet` is returned as unsolved object if algorithms
        to evaluate complete solutions are not yet implemented.

    `solveset_real` claims to be complete in the set of the solution it
    returns.

    Raises
    ======

    NotImplementedError
        Algorithms to solve inequalities in complex domain are
        not yet implemented.
    ValueError
        The input is not valid.
    RuntimeError
        It is a bug, please report to the github issue tracker.


    See Also
    =======

    solveset_complex : solver for complex domain

    Examples
    ========

    >>> from sympy import Symbol, exp, sin, sqrt, I
    >>> from sympy.solvers.solveset import solveset_real
    >>> x = Symbol('x', real=True)
    >>> a = Symbol('a', real=True, finite=True, positive=True)
    >>> solveset_real(x**2 - 1, x)
    {-1, 1}
    >>> solveset_real(sqrt(5*x + 6) - 2 - x, x)
    {-1, 2}
    >>> solveset_real(x - I, x)
    EmptySet()
    >>> solveset_real(x - a, x)
    {a}
    >>> solveset_real(exp(x) - a, x)
    {log(a)}

    * In case the equation has infinitely many solutions an infinitely indexed
      `ImageSet` is returned.

    >>> solveset_real(sin(x) - 1, x)
    ImageSet(Lambda(_n, 2*_n*pi + pi/2), Integers())

    * If the equation is true for any arbitrary value of the symbol a `S.Reals`
      set is returned.

    >>> solveset_real(x - x, x)
    (-oo, oo)

    """
    if not symbol.is_Symbol:
        raise ValueError(" %s is not a symbol" % (symbol))

    f = sympify(f)
    if not isinstance(f, (Expr, Number)):
        raise ValueError(" %s is not a valid sympy expression" % (f))

    original_eq = f
    f = together(f)

    # In this, unlike in solveset_complex, expression should only
    # be expanded when fraction(f)[1] does not contain the symbol
    # for which we are solving
    if not symbol in fraction(f)[1].free_symbols and f.is_rational_function():
        f = expand(f)

    if f.has(Piecewise):
        f = piecewise_fold(f)
    result = EmptySet()

    if f.expand().is_zero:
        return S.Reals
    elif not f.has(symbol):
        return EmptySet()
    elif f.is_Mul and all([_is_finite_with_finite_vars(m) for m in f.args]):
        # if f(x) and g(x) are both finite we can say that the solution of
        # f(x)*g(x) == 0 is same as Union(f(x) == 0, g(x) == 0) is not true in
        # general. g(x) can grow to infinitely large for the values where
        # f(x) == 0. To be sure that we are not silently allowing any
#.........这里部分代码省略.........