7 examples of 'python log2' in Python

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def log2(x):
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    try:
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        return math.log(x, 2)
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    except ValueError:
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        return float("nan")

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def log2 (x):
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    return math.log (x, 2)

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def log2(x):
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    """ Take log base 2 of x.
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    """
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    x = _fix_real_lt_zero(x)
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    return nx.log(x)/_ln2

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def log2(val):
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    """
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    Calculate the log base 2 of a value.
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    """
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    return int(math.log(val, 2))

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def log2(x):
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    """
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    Compute the logarithm base 2 of `x`.
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    Return the "principal value" (for a description of this, see
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    `numpy.log2`) of :math:`log_2(x)`. For real `x > 0`, this is
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    a real number (``log2(0)`` returns ``-inf`` and ``log2(np.inf)`` returns
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    ``inf``). Otherwise, the complex principle value is returned.
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    Parameters
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    ----------
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    x : array_like
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       The value(s) whose log base 2 is (are) required.
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    Returns
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    -------
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    out : ndarray or scalar
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       The log base 2 of the `x` value(s). If `x` was a scalar, so is `out`,
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       otherwise an array is returned.
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    See Also
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    --------
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    numpy.log2
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    Notes
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    -----
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    For a log2() that returns ``NAN`` when real `x < 0`, use `numpy.log2`
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    (note, however, that otherwise `numpy.log2` and this `log2` are
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    identical, i.e., both return ``-inf`` for `x = 0`, ``inf`` for `x = inf`,
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    and, notably, the complex principle value if ``x.imag != 0``).
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    Examples
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    --------
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    We set the printing precision so the example can be auto-tested:
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    >>> np.set_printoptions(precision=4)
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    >>> np.emath.log2(8)
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    3.0
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    >>> np.emath.log2([-4, -8, 8])
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    array([ 2.+4.5324j,  3.+4.5324j,  3.+0.j    ])
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    """
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    x = _fix_real_lt_zero(x)
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    return nx.log2(x)

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def log2(x):
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  return math.log(x)/math.log(2.)

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def exact_log2(number):
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  """Find and return an unsigned integer i >= 0 such that ``number == 2**i``. If
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  no such integer exists, this function raises ValueError.
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  .. NOTE:
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      It essentially answers this question:
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      "How many times would you have to multiply 2 into itself to
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      get the given number?"
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  Taken from PyCrypto.
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  :param number:
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      Unsigned integer.
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  :returns:
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      An integer i >= 0 such that number == 2**i.
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  """
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  num = number
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  if num <= 0:
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    raise ValueError("Cannot compute logarithm of non-positive integer")
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  i = 0
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  while num:
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    if (num & 1) and num != 1:
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      raise ValueError("No solution could be found")
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    i += 1
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    num >>= 1
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  i -= 1
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  #assert number == (1 << i)
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  return i