def __pow__(self, val):
     if not isscalar(val) or int(val) != val or val < 0:
         raise ValueError("Power to non-negative integers only.")
     res = [1]
     for _ in range(val):
         res = polymul(self.coeffs, res)
     return poly1d(res)

 def __rdiv__(self, other):
     if isscalar(other):
         return poly1d(other/self.coeffs)
     else:
         other = poly1d(other)
         return polydiv(other, self)

 def __div__(self, other):
     if isscalar(other):
         return poly1d(self.coeffs/other)
     else:
         other = poly1d(other)
         return polydiv(self, other)

 def __rmul__(self, other):
     if isscalar(other):
         return poly1d(other * self.coeffs)
     else:
         other = poly1d(other)
         return poly1d(polymul(self.coeffs, other.coeffs))

def assert_equal(actual,desired,err_msg='',verbose=True):
    """
    Raise an assertion if two objects are not equal.

    Given two objects (lists, tuples, dictionaries or numpy arrays), check
    that all elements of these objects are equal. An exception is raised at
    the first conflicting values.

    Parameters
    ----------
    actual : list, tuple, dict or ndarray
      The object to check.
    desired : list, tuple, dict or ndarray
      The expected object.
    err_msg : string
      The error message to be printed in case of failure.
    verbose : bool
      If True, the conflicting values are appended to the error message.

    Raises
    ------
    AssertionError
      If actual and desired are not equal.

    Examples
    --------
    >>> np.testing.assert_equal([4,5], [4,6])
    ...
    <type 'exceptions.AssertionError'>:
    Items are not equal:
    item=1
     ACTUAL: 5
     DESIRED: 6

    """
    if isinstance(desired, dict):
        if not isinstance(actual, dict) :
            raise AssertionError(repr(type(actual)))
        assert_equal(len(actual),len(desired),err_msg,verbose)
        for k,i in desired.items():
            if k not in actual :
                raise AssertionError(repr(k))
            assert_equal(actual[k], desired[k], 'key=%r\n%s' % (k,err_msg), verbose)
        return
    if isinstance(desired, (list,tuple)) and isinstance(actual, (list,tuple)):
        assert_equal(len(actual),len(desired),err_msg,verbose)
        for k in range(len(desired)):
            assert_equal(actual[k], desired[k], 'item=%r\n%s' % (k,err_msg), verbose)
        return
    from numpy.core import ndarray, isscalar, signbit
    from numpy.lib import iscomplexobj, real, imag
    if isinstance(actual, ndarray) or isinstance(desired, ndarray):
        return assert_array_equal(actual, desired, err_msg, verbose)
    msg = build_err_msg([actual, desired], err_msg, verbose=verbose)

    # Handle complex numbers: separate into real/imag to handle
    # nan/inf/negative zero correctly
    # XXX: catch ValueError for subclasses of ndarray where iscomplex fail
    try:
        usecomplex = iscomplexobj(actual) or iscomplexobj(desired)
    except ValueError:
        usecomplex = False

    if usecomplex:
        if iscomplexobj(actual):
            actualr = real(actual)
            actuali = imag(actual)
        else:
            actualr = actual
            actuali = 0
        if iscomplexobj(desired):
            desiredr = real(desired)
            desiredi = imag(desired)
        else:
            desiredr = desired
            desiredi = 0
        try:
            assert_equal(actualr, desiredr)
            assert_equal(actuali, desiredi)
        except AssertionError:
            raise AssertionError("Items are not equal:\n" \
                    "ACTUAL: %s\n" \
                    "DESIRED: %s\n" % (str(actual), str(desired)))

    # Inf/nan/negative zero handling
    try:
        # isscalar test to check cases such as [np.nan] != np.nan
        if isscalar(desired) != isscalar(actual):
            raise AssertionError(msg)

        # If one of desired/actual is not finite, handle it specially here:
        # check that both are nan if any is a nan, and test for equality
        # otherwise
        if not (gisfinite(desired) and gisfinite(actual)):
            isdesnan = gisnan(desired)
            isactnan = gisnan(actual)
            if isdesnan or isactnan:
                if not (isdesnan and isactnan):
                    raise AssertionError(msg)
            else:
#.........这里部分代码省略.........