def test_acos():
a = acos(interval(-0.5, 0.5))
assert a.start == np.arccos(0.5)
assert a.end == np.arccos(-0.5)
a = acos(interval(-1.5, 1.5))
assert a.is_valid is None
a = acos(interval(-2, -1.5))
assert a.is_valid is False
a = acos(interval(0, 2))
assert a.is_valid is None
a = acos(interval(2, 5))
assert a.is_valid is False
a = acos(0.5)
assert a.start == np.arccos(0.5)
assert a.end == np.arccos(0.5)
a = acos(1.5)
assert a.is_valid is False
def test_acos():
a = acos(interval(-0.5, 0.5))
assert a.start == np.arccos(0.5)
assert a.end == np.arccos(-0.5)
a = acos(interval(-1.5, 1.5))
assert a.is_valid is None
a = acos(interval(-2, -1.5))
assert a.is_valid is False
a = acos(interval(0, 2))
assert a.is_valid is None
a = acos(interval(2, 5))
assert a.is_valid is False
a = acos(0.5)
assert a.start == np.arccos(0.5)
assert a.end == np.arccos(0.5)
a = acos(1.5)
assert a.is_valid is False