numpy.testing.assert_array_almost_equal_nulp()

numpy.testing.assert_array_almost_equal_nulp(x, y, nulp=1) [source]

Compare two arrays relatively to their spacing.

This is a relatively robust method to compare two arrays whose amplitude is variable.

Parameters:

Parameters:	x, y : array_like Input arrays. nulp : int, optional The maximum number of unit in the last place for tolerance (see Notes). Default is 1.
Returns:	None
Raises:	AssertionError If the spacing between `x` and `y` for one or more elements is larger than `nulp`.

x, y : array_like

Input arrays.

nulp : int, optional

The maximum number of unit in the last place for tolerance (see Notes). Default is 1.

Returns:

None

Raises:

AssertionError

If the spacing between x and y for one or more elements is larger than nulp.

Notes

An assertion is raised if the following condition is not met:

abs(x - y) <= nulps * spacing(maximum(abs(x), abs(y)))

Examples

>>> x = np.array([1., 1e-10, 1e-20])
>>> eps = np.finfo(x.dtype).eps
>>> np.testing.assert_array_almost_equal_nulp(x, x*eps/2 + x)

>>> np.testing.assert_array_almost_equal_nulp(x, x*eps + x)
Traceback (most recent call last):
  ...
AssertionError: X and Y are not equal to 1 ULP (max is 2)

Links:

https://docs.scipy.org/doc/numpy-1.11.0/reference/generated/numpy.testing.assert_array_almost_equal_nulp.html

doc_NumPy

2017-01-10 18:18:54

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