SciPy

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 :

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.

See also

assert_array_max_ulp
Check that all items of arrays differ in at most N Units in the Last Place.
spacing
Return the distance between x and the nearest adjacent number.

Notes

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

abs(x - y) <= nulps * spacing(max(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)