Function assert_array_max_ulp

numpy/testing/_private/utils.py:1848–1896

Check that all items of arrays differ in at most N Units in the Last Place. Parameters ---------- a, b : array_like Input arrays to be compared. maxulp : int, optional The maximum number of units in the last place that elements of `a` and `b` can differ.

(a, b, maxulp=1, dtype=None)

def assert_array_max_ulp(a, b, maxulp=1, dtype=None):
    """
    Check that all items of arrays differ in at most N Units in the Last Place.

    Parameters
    ----------
    a, b : array_like
        Input arrays to be compared.
    maxulp : int, optional
        The maximum number of units in the last place that elements of `a` and
        `b` can differ. Default is 1.
    dtype : dtype, optional
        Data-type to convert `a` and `b` to if given. Default is None.

    Returns
    -------
    ret : ndarray
        Array containing number of representable floating point numbers between
        items in `a` and `b`.

    Raises
    ------
    AssertionError
        If one or more elements differ by more than `maxulp`.

    Notes
    -----
    For computing the ULP difference, this API does not differentiate between
    various representations of NAN (ULP difference between 0x7fc00000 and 0xffc00000
    is zero).

    See Also
    --------
    assert_array_almost_equal_nulp : Compare two arrays relatively to their
        spacing.

    Examples
    --------
    >>> a = np.linspace(0., 1., 100)
    >>> res = np.testing.assert_array_max_ulp(a, np.arcsin(np.sin(a)))

    """
    __tracebackhide__ = True  # Hide traceback for py.test
    import numpy as np
    ret = nulp_diff(a, b, dtype)
    if not np.all(ret <= maxulp):
        raise AssertionError(f"Arrays are not almost equal up to {maxulp:g} "
                             f"ULP (max difference is {np.max(ret):g} ULP)")
    return ret


def nulp_diff(x, y, dtype=None):