Python sympy.floor函数代码示例

def test_frac():
    assert isinstance(frac(x), frac)
    assert frac(oo) == AccumBounds(0, 1)
    assert frac(-oo) == AccumBounds(0, 1)

    assert frac(n) == 0
    assert frac(nan) == nan
    assert frac(Rational(4, 3)) == Rational(1, 3)
    assert frac(-Rational(4, 3)) == Rational(2, 3)

    r = Symbol('r', real=True)
    assert frac(I*r) == I*frac(r)
    assert frac(1 + I*r) == I*frac(r)
    assert frac(0.5 + I*r) == 0.5 + I*frac(r)
    assert frac(n + I*r) == I*frac(r)
    assert frac(n + I*k) == 0
    assert frac(x + I*x) == frac(x + I*x)
    assert frac(x + I*n) == frac(x)

    assert frac(x).rewrite(floor) == x - floor(x)
    assert frac(x).rewrite(ceiling) == x + ceiling(-x)
    assert frac(y).rewrite(floor).subs(y, pi) == frac(pi)
    assert frac(y).rewrite(floor).subs(y, -E) == frac(-E)
    assert frac(y).rewrite(ceiling).subs(y, -pi) == frac(-pi)
    assert frac(y).rewrite(ceiling).subs(y, E) == frac(E)

    assert Eq(frac(y), y - floor(y))
    assert Eq(frac(y), y + ceiling(-y))

def find_period_sqrt(x, ITS_MAX=20):
    #x = S(sqrt(x))
    x = np.sqrt(x)

    seq = array([], dtype=float64)
    for its in arange(ITS_MAX):
        # subtract the integer part
        y = x - floor(x)

        # put that into an array
        seq = hstack(( seq, floor(x).n() ))

        # take the inverse
        x = 1/y

    # boom, we have the sequence
    seq = seq[1:]
    l = len(seq)

    # find out how periodic it is
    for i in arange(0,10):
        # repeat some sequence
        tiled_array = tile(seq[:i-1], 10*l//i)
        # make it the right len
        tiled_array = tiled_array[:l]
        # see if they're equal
        if array_equal(tiled_array, seq):
            length = len(seq[:i-1])
            #print length
            #break
            return length
    #print -1
    return -1

def round_afz(val, ndigits=0):
    u"""Round using round-away-from-zero strategy for halfway cases.

    Python 3+ implements round-half-even, and Python 2.7 has a random behaviour
    from end user point of view (in fact, result depends on internal
    representation in floating point arithmetic).
    """
    ceil = math.ceil
    floor = math.floor
    val = float(val)
    if isnan(val) or isinf(val):
        return val
    s = repr(val).rstrip('0')
    if 'e' in s:
        # XXX: implement round-away-from-zero in this case too.
        return round(val, ndigits)
    sep = s.find('.')
    pos = sep + ndigits
    if ndigits <= 0:
        pos -= 1
    # Skip dot if needed to reach next digit.
    next_pos = (pos + 1 if pos + 1 != sep else pos + 2)
    if next_pos < 0 or next_pos == 0 and s[next_pos] == '-':
        return 0.
    if len(s) <= next_pos:
        # No need to round (no digit after).
        return val
    power = 10**ndigits
    if s[next_pos] in '01234':
        return (floor(val*power)/power if val > 0 else ceil(val*power)/power)
    else:
        return (ceil(val*power)/power if val > 0 else floor(val*power)/power)

    def _eval_expand_func(self, **hints):
        from sympy import exp, I, floor, Add, Poly, Dummy, exp_polar, unpolarify
        z, s, a = self.args
        if z == 1:
            return zeta(s, a)
        if s.is_Integer and s <= 0:
            t = Dummy('t')
            p = Poly((t + a)**(-s), t)
            start = 1/(1 - t)
            res = S(0)
            for c in reversed(p.all_coeffs()):
                res += c*start
                start = t*start.diff(t)
            return res.subs(t, z)

        if a.is_Rational:
            # See section 18 of
            #   Kelly B. Roach.  Hypergeometric Function Representations.
            #   In: Proceedings of the 1997 International Symposium on Symbolic and
            #   Algebraic Computation, pages 205-211, New York, 1997. ACM.
            # TODO should something be polarified here?
            add = S(0)
            mul = S(1)
            # First reduce a to the interaval (0, 1]
            if a > 1:
                n = floor(a)
                if n == a:
                    n -= 1
                a -= n
                mul = z**(-n)
                add = Add(*[-z**(k - n)/(a + k)**s for k in xrange(n)])
            elif a <= 0:
                n = floor(-a) + 1
                a += n
                mul = z**n
                add = Add(*[z**(n - 1 - k)/(a - k - 1)**s for k in xrange(n)])

            m, n = S([a.p, a.q])
            zet = exp_polar(2*pi*I/n)
            root = z**(1/n)
            return add + mul*n**(s - 1)*Add(
                *[polylog(s, zet**k*root)._eval_expand_func(**hints)
                  / (unpolarify(zet)**k*root)**m for k in xrange(n)])

        # TODO use minpoly instead of ad-hoc methods when issue 2789 is fixed
        if z.func is exp and (z.args[0]/(pi*I)).is_Rational or z in [-1, I, -I]:
            # TODO reference?
            if z == -1:
                p, q = S([1, 2])
            elif z == I:
                p, q = S([1, 4])
            elif z == -I:
                p, q = S([-1, 4])
            else:
                arg = z.args[0]/(2*pi*I)
                p, q = S([arg.p, arg.q])
            return Add(*[exp(2*pi*I*k*p/q)/q**s*zeta(s, (k + a)/q)
                         for k in xrange(q)])

        return lerchphi(z, s, a)

def rationalize(x, maxcoeff=10000):
    """
    Helps identifying a rational number from a float (or mpmath.mpf) value by
    using a continued fraction. The algorithm stops as soon as a large partial
    quotient is detected (greater than 10000 by default).

    Examples
    ========

    >>> from sympy.concrete.guess import rationalize
    >>> from mpmath import cos, pi
    >>> rationalize(cos(pi/3))
    1/2

    >>> from mpmath import mpf
    >>> rationalize(mpf("0.333333333333333"))
    1/3

    While the function is rather intended to help 'identifying' rational
    values, it may be used in some cases for approximating real numbers.
    (Though other functions may be more relevant in that case.)

    >>> rationalize(pi, maxcoeff = 250)
    355/113

    See also
    ========
    Several other methods can approximate a real number as a rational, like:

      * fractions.Fraction.from_decimal
      * fractions.Fraction.from_float
      * mpmath.identify
      * mpmath.pslq by using the following syntax: mpmath.pslq([x, 1])
      * mpmath.findpoly by using the following syntax: mpmath.findpoly(x, 1)
      * sympy.simplify.nsimplify (which is a more general function)

    The main difference between the current function and all these variants is
    that control focuses on magnitude of partial quotients here rather than on
    global precision of the approximation. If the real is "known to be" a
    rational number, the current function should be able to detect it correctly
    with the default settings even when denominator is great (unless its
    expansion contains unusually big partial quotients) which may occur
    when studying sequences of increasing numbers. If the user cares more
    on getting simple fractions, other methods may be more convenient.

    """
    p0, p1 = 0, 1
    q0, q1 = 1, 0
    a = floor(x)
    while a < maxcoeff or q1 == 0:
        p = a * p1 + p0
        q = a * q1 + q0
        p0, p1 = p1, p
        q0, q1 = q1, q
        if x == a:
            break
        x = 1 / (x - a)
        a = floor(x)
    return sympify(p) / q

def test_dir():
    assert abs(x).series(x, 0, dir="+") == x
    assert abs(x).series(x, 0, dir="-") == -x
    assert floor(x + 2).series(x, 0, dir='+') == 2
    assert floor(x + 2).series(x, 0, dir='-') == 1
    assert floor(x + 2.2).series(x, 0, dir='-') == 2
    assert ceiling(x + 2.2).series(x, 0, dir='-') == 3
    assert sin(x + y).series(x, 0, dir='-') == sin(x + y).series(x, 0, dir='+')

def rightshift(a, b):
    if issig('rr', a, b):
        return Real(int(sym.floor(a)) >> int(sym.floor(b)))

    if issig('qr', a, b):
        b = sym.floor(b)
        return a[-b:] + a[:-b]

    raise BadTypeCombinationError('rightshift', a, b)

def leftshift(a, b):
    if issig('rr', a, b):
        return Real(int(sym.floor(a)) << int(sym.floor(b)))

    if issig('qr', a, b):
        b = sym.floor(b)
        return a[b:] + a[:b]

    raise BadTypeCombinationError('leftshift', a, b)

def test_issue_8444_workingtests():
    x = symbols('x')
    assert Gt(x, floor(x)) == Gt(x, floor(x), evaluate=False)
    assert Ge(x, floor(x)) == Ge(x, floor(x), evaluate=False)
    assert Lt(x, ceiling(x)) == Lt(x, ceiling(x), evaluate=False)
    assert Le(x, ceiling(x)) == Le(x, ceiling(x), evaluate=False)
    i = symbols('i', integer=True)
    assert (i > floor(i)) == False
    assert (i < ceiling(i)) == False

def test_issue_8444_nonworkingtests():
    x = symbols('x', real=True)
    assert (x <= oo) == (x >= -oo) == True

    x = symbols('x')
    assert x >= floor(x)
    assert (x < floor(x)) == False
    assert x <= ceiling(x)
    assert (x > ceiling(x)) == False

def test_dir():
    x = Symbol('x')
    y = Symbol('y')
    assert abs(x).series(x, 0, dir="+") == x
    assert abs(x).series(x, 0, dir="-") == -x
    assert floor(x+2).series(x,0,dir='+') == 2
    assert floor(x+2).series(x,0,dir='-') == 1
    assert floor(x+2.2).series(x,0,dir='-') == 2
    assert sin(x+y).series(x,0,dir='-') == sin(x+y).series(x,0,dir='+')

def length(P, Q, D):
    """
    Returns the length of aperiodic part + length of periodic part of
    continued fraction representation of (P + sqrt(D))/Q. It is important
    to remember that this does NOT return the length of the periodic
    part but the addition of the legths of the two parts as mentioned above.

    Usage
    =====

        length(P, Q, D) -> P, Q and D are integers corresponding to the
        continued fraction (P + sqrt(D))/Q.

    Details
    =======

        ``P`` corresponds to the P in the continued fraction, (P + sqrt(D))/ Q
        ``D`` corresponds to the D in the continued fraction, (P + sqrt(D))/ Q
        ``Q`` corresponds to the Q in the continued fraction, (P + sqrt(D))/ Q

    Examples
    ========

    >>> from sympy.solvers.diophantine import length
    >>> length(-2 , 4, 5) # (-2 + sqrt(5))/4
    3
    >>> length(-5, 4, 17) # (-5 + sqrt(17))/4
    4
    """
    x = P + sqrt(D)
    y = Q

    x = sympify(x)
    v, res = [], []
    q = x/y

    if q < 0:
        v.append(q)
        res.append(floor(q))
        q = q - floor(q)
        num, den = rad_rationalize(1, q)
        q = num / den

    while 1:
        v.append(q)
        a = int(q)
        res.append(a)

        if q == a:
            return len(res)

        num, den = rad_rationalize(1,(q - a))
        q = num / den

        if q in v:
            return len(res)

def test_dir():
    x = Symbol("x")
    y = Symbol("y")
    assert abs(x).series(x, 0, dir="+") == x
    assert abs(x).series(x, 0, dir="-") == -x
    assert floor(x + 2).series(x, 0, dir="+") == 2
    assert floor(x + 2).series(x, 0, dir="-") == 1
    assert floor(x + 2.2).series(x, 0, dir="-") == 2
    assert ceiling(x + 2.2).series(x, 0, dir="-") == 3
    assert sin(x + y).series(x, 0, dir="-") == sin(x + y).series(x, 0, dir="+")

def test_series():
    x, y = symbols('x,y')
    assert floor(x).nseries(x, y, 100) == floor(y)
    assert ceiling(x).nseries(x, y, 100) == ceiling(y)
    assert floor(x).nseries(x, pi, 100) == 3
    assert ceiling(x).nseries(x, pi, 100) == 4
    assert floor(x).nseries(x, 0, 100) == 0
    assert ceiling(x).nseries(x, 0, 100) == 1
    assert floor(-x).nseries(x, 0, 100) == -1
    assert ceiling(-x).nseries(x, 0, 100) == 0

def test_upretty_floor():
    assert upretty(floor(x)) == u'⌊x⌋'

    u = upretty( floor(1 / (y - floor(x))) )
    s = \
u"""\
⎢   1   ⎥
⎢───────⎥
⎣y - ⌊x⌋⎦\
"""
    assert u == s