def test_sqrt(): a = sqrt(interval(1, 4)) assert a.start == 1 assert a.end == 2 a = sqrt(interval(0.01, 1)) assert a.start == np.sqrt(0.01) assert a.end == 1 a = sqrt(interval(-1, 1)) assert a.is_valid is None a = sqrt(interval(-3, -1)) assert a.is_valid is False a = sqrt(4) assert (a == interval(2, 2)) == (True, True) a = sqrt(-3) assert a.is_valid is False