Python simplify._is_sum_surds函数代码示例

def _minimal_polynomial_sq(p, n, x):
    """
    Returns the minimal polynomial for the ``nth-root`` of a sum of surds
    or ``None`` if it fails.

    Parameters
    ==========

    p : sum of surds
    n : positive integer
    x : variable of the returned polynomial

    Examples
    ========

    >>> from sympy.polys.numberfields import _minimal_polynomial_sq
    >>> from sympy import sqrt
    >>> from sympy.abc import x
    >>> q = 1 + sqrt(2) + sqrt(3)
    >>> _minimal_polynomial_sq(q, 3, x)
    x**12 - 4*x**9 - 4*x**6 + 16*x**3 - 8

    """
    from sympy.simplify.simplify import _is_sum_surds

    p = sympify(p)
    n = sympify(n)
    r = _is_sum_surds(p)
    if not n.is_Integer or not n > 0 or not _is_sum_surds(p):
        return None
    pn = p**Rational(1, n)
    # eliminate the square roots
    p -= x
    while 1:
        p1 = _separate_sq(p)
        if p1 is p:
            p = p1.subs({x:x**n})
            break
        else:
            p = p1

    # _separate_sq eliminates field extensions in a minimal way, so that
    # if n = 1 then `p = constant*(minimal_polynomial(p))`
    # if n > 1 it contains the minimal polynomial as a factor.
    if n == 1:
        p1 = Poly(p)
        if p.coeff(x**p1.degree(x)) < 0:
            p = -p
        p = p.primitive()[1]
        return p
    # by construction `p` has root `pn`
    # the minimal polynomial is the factor vanishing in x = pn
    factors = factor_list(p)[1]

    result = _choose_factor(factors, x, pn)
    return result

def _minpoly_compose(ex, x, dom):
    """
    Computes the minimal polynomial of an algebraic element
    using operations on minimal polynomials

    Examples
    ========

    >>> from sympy import minimal_polynomial, sqrt, Rational
    >>> from sympy.abc import x, y
    >>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True)
    x**2 - 2*x - 1
    >>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True)
    x**2*y**2 - 2*x*y - y**3 + 1

    """
    if ex.is_Rational:
        return ex.q*x - ex.p
    if ex is I:
        return x**2 + 1
    if hasattr(dom, 'symbols') and ex in dom.symbols:
        return x - ex

    if dom.is_QQ and _is_sum_surds(ex):
        # eliminate the square roots
        ex -= x
        while 1:
            ex1 = _separate_sq(ex)
            if ex1 is ex:
                return ex
            else:
                ex = ex1

    if ex.is_Add:
        res = _minpoly_add(x, dom, *ex.args)
    elif ex.is_Mul:
        res = _minpoly_mul(x, dom, *ex.args)
    elif ex.is_Pow:
        res = _minpoly_pow(ex.base, ex.exp, x, dom)
    elif ex.__class__ is C.sin:
        res = _minpoly_sin(ex, x)
    elif ex.__class__ is C.cos:
        res = _minpoly_cos(ex, x)
    elif ex.__class__ is C.exp:
        res = _minpoly_exp(ex, x)
    elif ex.__class__ is RootOf:
        res = _minpoly_rootof(ex, x)
    else:
        raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex)
    return res

def _minpoly1(ex, x):
    """
    Computes the minimal polynomial of an algebraic number
    using operations on minimal polynomials

    Examples
    ========

    >>> from sympy import minimal_polynomial, sqrt, Rational
    >>> from sympy.abc import x
    >>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True)
    x**2 - 2*x - 1
    """
    if ex.is_Rational:
        return ex.q*x - ex.p
    if ex is I:
        return x**2 + 1

    if _is_sum_surds(ex):
        # eliminate the square roots
        ex -= x
        while 1:
            ex1 = _separate_sq(ex)
            if ex1 is ex:
                return ex
            else:
                ex = ex1

    if ex.is_Add:
        res = _minpoly_add(x, *ex.args)
    elif ex.is_Mul:
        res = _minpoly_mul(x, *ex.args)
    elif ex.is_Pow:
        res = _minpoly_pow(ex.base, ex.exp, x)
    elif ex.__class__ is C.sin:
        res = _minpoly_sin(ex, x)
    elif ex.__class__ is C.cos:
        res = _minpoly_cos(ex, x)
    elif ex.__class__ is C.exp:
        res = _minpoly_exp(ex, x)
    elif ex.__class__ is RootOf:
        res = _minpoly_rootof(ex, x)
    else:
        raise NotAlgebraic("%s doesn't seem to be an algebraic number" % ex)
    return res

#.........这里部分代码省略.........
            elif ex.is_Rational:
                return ex
        elif ex.is_Add:
            return Add(*[ bottom_up_scan(g) for g in ex.args ])
        elif ex.is_Mul:
            return Mul(*[ bottom_up_scan(g) for g in ex.args ])
        elif ex.is_Pow:
            if ex.exp.is_Rational:
                if ex.exp < 0 and ex.base.is_Add:
                    coeff, terms = ex.base.as_coeff_add()
                    elt, _ = primitive_element(terms, polys=True)

                    alg = ex.base - coeff

                    # XXX: turn this into eval()
                    inverse = invert(elt.gen + coeff, elt).as_expr()
                    base = inverse.subs(elt.gen, alg).expand()

                    if ex.exp == -1:
                        return bottom_up_scan(base)
                    else:
                        ex = base**(-ex.exp)
                if not ex.exp.is_Integer:
                    base, exp = (
                        ex.base**ex.exp.p).expand(), Rational(1, ex.exp.q)
                else:
                    base, exp = ex.base, ex.exp
                base = bottom_up_scan(base)
                expr = base**exp

                if expr not in mapping:
                    return update_mapping(expr, 1/exp, -base)
                else:
                    return symbols[expr]
        elif ex.is_AlgebraicNumber:
            if ex.root not in mapping:
                return update_mapping(ex.root, ex.minpoly)
            else:
                return symbols[ex.root]

        raise NotAlgebraic("%s doesn't seem to be an algebraic number" % ex)

    def simpler_inverse(ex):
        """
        Returns True if it is more likely that the minimal polynomial
        algorithm works better with the inverse
        """
        if ex.is_Pow:
            if (1/ex.exp).is_integer and ex.exp < 0:
                if ex.base.is_Add:
                    return True
        if ex.is_Mul:
            hit = True
            a = []
            for p in ex.args:
                if p.is_Add:
                    return False
                if p.is_Pow:
                    if p.base.is_Add and p.exp > 0:
                        return False

            if hit:
                return True
        return False

    inverted = False
    ex = expand_multinomial(ex)
    if ex.is_AlgebraicNumber:
        return ex.minpoly.as_expr(x)
    elif ex.is_Rational:
        result = ex.q*x - ex.p
    else:
        inverted = simpler_inverse(ex)
        if inverted:
            ex = ex**-1
        res = None
        if ex.is_Pow and (1/ex.exp).is_Integer:
            n = 1/ex.exp
            res = _minimal_polynomial_sq(ex.base, n, x)

        elif _is_sum_surds(ex):
            res = _minimal_polynomial_sq(ex, S.One, x)

        if res is not None:
            result = res

        if res is None:
            bus = bottom_up_scan(ex)
            F = [x - bus] + list(mapping.values())
            G = groebner(F, list(symbols.values()) + [x], order='lex')

            _, factors = factor_list(G[-1])
            # by construction G[-1] has root `ex`
            result = _choose_factor(factors, x, ex)
    if inverted:
        result = _invertx(result, x)
        if result.coeff(x**degree(result, x)) < 0:
            result = expand_mul(-result)

    return result

def _minpoly_compose(ex, x, dom):
    """
    Computes the minimal polynomial of an algebraic element
    using operations on minimal polynomials

    Examples
    ========

    >>> from sympy import minimal_polynomial, sqrt, Rational
    >>> from sympy.abc import x, y
    >>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True)
    x**2 - 2*x - 1
    >>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True)
    x**2*y**2 - 2*x*y - y**3 + 1

    """
    if ex.is_Rational:
        return ex.q*x - ex.p
    if ex is I:
        return x**2 + 1
    if hasattr(dom, 'symbols') and ex in dom.symbols:
        return x - ex

    if dom.is_QQ and _is_sum_surds(ex):
        # eliminate the square roots
        ex -= x
        while 1:
            ex1 = _separate_sq(ex)
            if ex1 is ex:
                return ex
            else:
                ex = ex1

    if ex.is_Add:
        res = _minpoly_add(x, dom, *ex.args)
    elif ex.is_Mul:
        f = Factors(ex).factors
        r = sift(f.items(), lambda itx: itx[0].is_rational and itx[1].is_rational)
        if r[True] and dom == QQ:
            ex1 = Mul(*[bx**ex for bx, ex in r[False] + r[None]])
            r1 = r[True]
            dens = [y.q for _, y in r1]
            lcmdens = reduce(lcm, dens, 1)
            nums = [base**(y.p*lcmdens // y.q) for base, y in r1]
            ex2 = Mul(*nums)
            mp1 = minimal_polynomial(ex1, x)
            # use the fact that in SymPy canonicalization products of integers
            # raised to rational powers are organized in relatively prime
            # bases, and that in ``base**(n/d)`` a perfect power is
            # simplified with the root
            mp2 = ex2.q*x**lcmdens - ex2.p
            ex2 = ex2**Rational(1, lcmdens)
            res = _minpoly_op_algebraic_element(Mul, ex1, ex2, x, dom, mp1=mp1, mp2=mp2)
        else:
            res = _minpoly_mul(x, dom, *ex.args)
    elif ex.is_Pow:
        res = _minpoly_pow(ex.base, ex.exp, x, dom)
    elif ex.__class__ is C.sin:
        res = _minpoly_sin(ex, x)
    elif ex.__class__ is C.cos:
        res = _minpoly_cos(ex, x)
    elif ex.__class__ is C.exp:
        res = _minpoly_exp(ex, x)
    elif ex.__class__ is RootOf:
        res = _minpoly_rootof(ex, x)
    else:
        raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex)
    return res

#.........这里部分代码省略.........
            return Mul(*[ bottom_up_scan(g) for g in ex.args ])
        elif ex.is_Pow:
            if ex.exp.is_Rational:
                if ex.exp < 0 and ex.base.is_Add:
                    coeff, terms = ex.base.as_coeff_add()
                    elt, _ = primitive_element(terms, polys=True)

                    alg = ex.base - coeff

                    # XXX: turn this into eval()
                    inverse = invert(elt.gen + coeff, elt).as_expr()
                    base = inverse.subs(elt.gen, alg).expand()

                    if ex.exp == -1:
                        return bottom_up_scan(base)
                    else:
                        ex = base**(-ex.exp)
                if not ex.exp.is_Integer:
                    base, exp = (
                        ex.base**ex.exp.p).expand(), Rational(1, ex.exp.q)
                else:
                    base, exp = ex.base, ex.exp
                base = bottom_up_scan(base)
                expr = base**exp

                if expr not in mapping:
                    return update_mapping(expr, 1/exp, -base)
                else:
                    return symbols[expr]
        elif ex.is_AlgebraicNumber:
            if ex.root not in mapping:
                return update_mapping(ex.root, ex.minpoly)
            else:
                return symbols[ex.root]

        raise NotAlgebraic("%s doesn't seem to be an algebraic number" % ex)

    def simpler_inverse(ex):
        """
        Returns True if it is more likely that the minimal polynomial
        algorithm works better with the inverse
        """
        if ex.is_Pow:
            if (1/ex.exp).is_integer and ex.exp < 0:
                if ex.base.is_Add:
                    return True
        if ex.is_Mul:
            hit = True
            a = []
            for p in ex.args:
                if p.is_Add:
                    return False
                if p.is_Pow:
                    if p.base.is_Add and p.exp > 0:
                        return False

            if hit:
                return True
        return False

    inverted = False
    ex = expand_multinomial(ex)
    if ex.is_AlgebraicNumber:
        if not polys:
            return ex.minpoly.as_expr(x)
        else:
            return ex.minpoly.replace(x)
    elif ex.is_Rational:
        result = ex.q*x - ex.p
    else:
        inverted = simpler_inverse(ex)
        if inverted:
            ex = ex**-1
        res = None
        if ex.is_Pow and (1/ex.exp).is_Integer:
            n = 1/ex.exp
            res = _minimal_polynomial_sq(ex.base, n, x)

        elif _is_sum_surds(ex):
            res = _minimal_polynomial_sq(ex, S.One, x)

        if res is not None:
            result = res

        if res is None:
            bus = bottom_up_scan(ex)
            F = [x - bus] + mapping.values()
            G = groebner(F, symbols.values() + [x], order='lex')

            _, factors = factor_list(G[-1])
            # by construction G[-1] has root `ex`
            result = _choose_factor(factors, x, ex)
    if inverted:
        result = _invertx(result, x)
        if result.coeff(x**degree(result, x)) < 0:
            result = expand_mul(-result)
    if polys:
        return cls(result, x, field=True)
    else:
        return result

def minimal_polynomial(ex, x=None, **args):
    """
    Computes the minimal polynomial of an algebraic number.

    Examples
    ========

    >>> from sympy import minimal_polynomial, sqrt
    >>> from sympy.abc import x

    >>> minimal_polynomial(sqrt(2), x)
    x**2 - 2
    >>> minimal_polynomial(sqrt(2) + sqrt(3), x)
    x**4 - 10*x**2 + 1

    """
    from sympy.polys.polytools import degree
    from sympy.core.function import expand_mul, expand_multinomial
    from sympy.simplify.simplify import _is_sum_surds

    generator = numbered_symbols("a", cls=Dummy)
    mapping, symbols, replace = {}, {}, []

    ex = sympify(ex)

    if x is not None:
        x, cls = sympify(x), Poly
    else:
        x, cls = Dummy("x"), PurePoly

    def update_mapping(ex, exp, base=None):
        a = generator.next()
        symbols[ex] = a

        if base is not None:
            mapping[ex] = a ** exp + base
        else:
            mapping[ex] = exp.as_expr(a)

        return a

    def bottom_up_scan(ex):
        if ex.is_Atom:
            if ex is S.ImaginaryUnit:
                if ex not in mapping:
                    return update_mapping(ex, 2, 1)
                else:
                    return symbols[ex]
            elif ex.is_Rational:
                return ex
        elif ex.is_Add:
            return Add(*[bottom_up_scan(g) for g in ex.args])
        elif ex.is_Mul:
            return Mul(*[bottom_up_scan(g) for g in ex.args])
        elif ex.is_Pow:
            if ex.exp.is_Rational:
                if ex.exp < 0 and ex.base.is_Add:
                    coeff, terms = ex.base.as_coeff_add()
                    elt, _ = primitive_element(terms, polys=True)

                    alg = ex.base - coeff

                    # XXX: turn this into eval()
                    inverse = invert(elt.gen + coeff, elt).as_expr()
                    base = inverse.subs(elt.gen, alg).expand()

                    if ex.exp == -1:
                        return bottom_up_scan(base)
                    else:
                        ex = base ** (-ex.exp)
                if not ex.exp.is_Integer:
                    base, exp = (ex.base ** ex.exp.p).expand(), Rational(1, ex.exp.q)
                else:
                    base, exp = ex.base, ex.exp
                base = bottom_up_scan(base)
                expr = base ** exp

                if expr not in mapping:
                    return update_mapping(expr, 1 / exp, -base)
                else:
                    return symbols[expr]
        elif ex.is_AlgebraicNumber:
            if ex.root not in mapping:
                return update_mapping(ex.root, ex.minpoly)
            else:
                return symbols[ex.root]

        raise NotAlgebraic("%s doesn't seem to be an algebraic number" % ex)

    def simpler_inverse(ex):
        """
        Returns True if it is more likely that the minimal polynomial
        algorithm works better with the inverse
        """
        if ex.is_Pow:
            if (1 / ex.exp).is_integer and ex.exp < 0:
                if ex.base.is_Add:
                    return True
        if ex.is_Mul:
            hit = True
#.........这里部分代码省略.........