Python sympy.logcombine函数代码示例

def test_logcombine_complex_coeff():
    # TODO: Make the expand() call in logcombine smart enough so that both
    # these hold.
    assert logcombine(Integral((sin(x**2)+cos(x**3))/x, x), force=True) == \
        Integral((sin(x**2)+cos(x**3))/x, x)
    assert logcombine(Integral((sin(x**2)+cos(x**3))/x, x)+ (2+3*I)*log(x), \
        force=True) == log(x**2)+3*I*log(x) + \
        Integral((sin(x**2)+cos(x**3))/x, x)

def test_logcombine_2():
    # The same as one of the tests above, but with Rational(a,b) replaced with a/b.
    # This fails because of a bug in matches.  See issue 1274.
    x, y = symbols("xy")
    assert logcombine((x*y+sqrt(x**4+y**4)+log(x)-log(y))/(pi*x**(2/3)*y**(3/2)), \
        assume_pos_real=True) == log(x**(1/(pi*x**(2/3)*y**(3/2)))*y**(-1/\
        (pi*x**(2/3)*y**(3/2)))) + (x**4 + y**4)**(1/2)/(pi*x**(2/3)*y**(3/2)) + \
        x**(1/3)/(pi*y**(1/2))

    def logcombine_include_negative_power(expr, force=False):
        """Perform a more powerful logcombine than SymPy's logcombine.

        In SymPy:
        logcombine(-log(x)) = -log(x), rather than log(1/x).

        This behaviour is implemented here.

        >>> SolveLogEquation.logcombine_include_negative_power(-sympy.log(2 * x + 1))
        log(1/(2*x + 1))
        """

        expr = sympy.logcombine(expr, force)

        if expr.could_extract_minus_sign():
            interior = expr.match(coeff0 * sympy.log(x0))[x0]
            expr *= -1
            expr = sympy.log(1 / interior)

        return expr

    def log_solver(expr, check_validity=False):
        """Return valid solutions (i.e. solutions that don't evaluate any log that's part of the expression as complex)
        for an expression that is the addition/subtraction of logs.

        >>> SolveLogEquation.log_solver(sympy.log(x - 1))
        [2]

        >>> SolveLogEquation.log_solver(sympy.log(3 * x - 2) - 2 * sympy.log(x))
        [1, 2]
        """

        single_log = sympy.logcombine(expr, force=True)
        interior = single_log.match(coeff0 * sympy.log(x0))[x0]

        numerator, denominator = interior.as_numer_denom()

        solutions = sympy.solve(numerator - denominator)

        if check_validity:
            return [solution for solution in solutions if SolveLogEquation.is_valid_solution(expr, solution)]
        else:
            return solutions

    def normalize_transformations(w):
        # same as
        #    lambda w: w.doit().expand().ratsimp().expand()
        # except catch Polynomial error that could be triggered by ratsimp()
        # and catch attribute error for objects like Interval
        from sympy import PolynomialError

        w = w.doit()
        try:
            w = w.expand()
        except (AttributeError, TypeError):
            pass
        if w.has(sympy_log):
            from sympy import logcombine

            try:
                w = logcombine(w)
            except TypeError:
                pass
        try:
            w = w.ratsimp().expand()
        except (AttributeError, PolynomialError, UnicodeEncodeError, TypeError):
            pass
        return w

 def mysimp(expr):
     from sympy import expand, logcombine, powsimp
     return expand(
         powsimp(logcombine(expr, force=True), force=True, deep=True),
         force=True).replace(exp_polar, exp)

def test_logcombine_1():
    x, y = symbols("x,y")
    a = Symbol("a")
    z, w = symbols("z,w", positive=True)
    b = Symbol("b", real=True)
    assert logcombine(log(x)+2*log(y)) == log(x) + 2*log(y)
    assert logcombine(log(x)+2*log(y), force=True) == log(x*y**2)
    assert logcombine(a*log(w)+log(z)) == a*log(w) + log(z)
    assert logcombine(b*log(z)+b*log(x)) == log(z**b) + b*log(x)
    assert logcombine(b*log(z)-log(w)) == log(z**b/w)
    assert logcombine(log(x)*log(z)) == log(x)*log(z)
    assert logcombine(log(w)*log(x)) == log(w)*log(x)
    assert logcombine(cos(-2*log(z)+b*log(w))) in [cos(log(w**b/z**2)),
                                                   cos(log(z**2/w**b))]
    assert logcombine(log(log(x)-log(y))-log(z), force=True) == \
        log(log((x/y)**(1/z)))
    assert logcombine((2+I)*log(x), force=True) == I*log(x)+log(x**2)
    assert logcombine((x**2+log(x)-log(y))/(x*y), force=True) == \
        log(x**(1/(x*y))*y**(-1/(x*y)))+x/y
    assert logcombine(log(x)*2*log(y)+log(z), force=True) == \
        log(z*y**log(x**2))
    assert logcombine((x*y+sqrt(x**4+y**4)+log(x)-log(y))/(pi*x**Rational(2, 3)*\
        sqrt(y)**3), force=True) == \
        log(x**(1/(pi*x**Rational(2, 3)*sqrt(y)**3))*y**(-1/(pi*\
        x**Rational(2, 3)*sqrt(y)**3))) + sqrt(x**4 + y**4)/(pi*\
        x**Rational(2, 3)*sqrt(y)**3) + x**Rational(1, 3)/(pi*sqrt(y))
    assert logcombine(Eq(log(x), -2*log(y)), force=True) == \
        Eq(log(x*y**2), Integer(0))
    assert logcombine(Eq(y, x*acos(-log(x/y))), force=True) == \
        Eq(y, x*acos(log(y/x)))
    assert logcombine(gamma(-log(x/y))*acos(-log(x/y)), force=True) == \
        acos(log(y/x))*gamma(log(y/x))
    assert logcombine((2+3*I)*log(x), force=True) == \
        log(x**2)+3*I*log(x)
    assert logcombine(Eq(y, -log(x)), force=True) == Eq(y, log(1/x))
    assert logcombine(Integral((sin(x**2)+cos(x**3))/x, x), force=True) == \
        Integral((sin(x**2)+cos(x**3))/x, x)
    assert logcombine(Integral((sin(x**2)+cos(x**3))/x, x)+ (2+3*I)*log(x), \
        force=True) == log(x**2)+3*I*log(x) + \
        Integral((sin(x**2)+cos(x**3))/x, x)

    def eval(cls, arg):
        from sympy.assumptions import ask, Q
        from sympy.calculus import AccumBounds
        from sympy.sets.setexpr import SetExpr
        from sympy.matrices.matrices import MatrixBase
        from sympy import logcombine
        if arg.is_Number:
            if arg is S.NaN:
                return S.NaN
            elif arg is S.Zero:
                return S.One
            elif arg is S.One:
                return S.Exp1
            elif arg is S.Infinity:
                return S.Infinity
            elif arg is S.NegativeInfinity:
                return S.Zero
        elif arg is S.ComplexInfinity:
            return S.NaN
        elif isinstance(arg, log):
            return arg.args[0]
        elif isinstance(arg, AccumBounds):
            return AccumBounds(exp(arg.min), exp(arg.max))
        elif isinstance(arg, SetExpr):
            return arg._eval_func(cls)
        elif arg.is_Mul:
            if arg.is_number or arg.is_Symbol:
                coeff = arg.coeff(S.Pi*S.ImaginaryUnit)
                if coeff:
                    if ask(Q.integer(2*coeff)):
                        if ask(Q.even(coeff)):
                            return S.One
                        elif ask(Q.odd(coeff)):
                            return S.NegativeOne
                        elif ask(Q.even(coeff + S.Half)):
                            return -S.ImaginaryUnit
                        elif ask(Q.odd(coeff + S.Half)):
                            return S.ImaginaryUnit

            # Warning: code in risch.py will be very sensitive to changes
            # in this (see DifferentialExtension).

            # look for a single log factor

            coeff, terms = arg.as_coeff_Mul()

            # but it can't be multiplied by oo
            if coeff in [S.NegativeInfinity, S.Infinity]:
                return None

            coeffs, log_term = [coeff], None
            for term in Mul.make_args(terms):
                term_ = logcombine(term)
                if isinstance(term_, log):
                    if log_term is None:
                        log_term = term_.args[0]
                    else:
                        return None
                elif term.is_comparable:
                    coeffs.append(term)
                else:
                    return None

            return log_term**Mul(*coeffs) if log_term else None

        elif arg.is_Add:
            out = []
            add = []
            for a in arg.args:
                if a is S.One:
                    add.append(a)
                    continue
                newa = cls(a)
                if isinstance(newa, cls):
                    add.append(a)
                else:
                    out.append(newa)
            if out:
                return Mul(*out)*cls(Add(*add), evaluate=False)

        elif isinstance(arg, MatrixBase):
            return arg.exp()