def METHOD_NAME(dtype):
    # Deterministic test for fillpositive threshold
    # We are trying to fill (x, y, z) with a w such that |(w, x, y, z)| == 1
    # If |(x, y, z)| is slightly off one, w should still be 0
    nptype = np.dtype(dtype).type
    # Obviously, |(x, y, z)| == 1
    baseline = np.array([0, 0, 1], dtype=dtype)
    # Obviously, |(x, y, z)| ~ 1
    plus = baseline * nptype(1 + np.finfo(dtype).eps)
    minus = baseline * nptype(1 - np.finfo(dtype).eps)
    assert nq.fillpositive(plus)[0] == 0.0
    assert nq.fillpositive(minus)[0] == 0.0
    # |(x, y, z)| > 1, no real solutions
    plus = baseline * nptype(1 + 2 * np.finfo(dtype).eps)
    with pytest.raises(ValueError):
        nq.fillpositive(plus)
    # |(x, y, z)| < 1, two real solutions, we choose positive
    minus = baseline * nptype(1 - 2 * np.finfo(dtype).eps)
    assert nq.fillpositive(minus)[0] > 0.0