def test_cen_diff4_zero_slope(self):
np.testing.assert_array_equal(calcs.cen_diff4(self.ones, self.arange),
self.zeros_trunc4)
np.testing.assert_array_equal(calcs.cen_diff4(self.zeros, self.arange),
self.zeros_trunc4)
np.testing.assert_array_equal(calcs.cen_diff4(self.zeros, 1.),
self.zeros_trunc4)
def test_cen_diff4_constant_slope(self):
np.testing.assert_array_equal(calcs.cen_diff4(self.arange, 1.),
self.ones_trunc4)
np.testing.assert_array_equal(calcs.cen_diff4(self.arange * -2.5, 1.),
self.ones_trunc4 * -2.5)
