def test_cosh(): a = cosh(interval(1, 2)) assert a.start == np.cosh(1) assert a.end == np.cosh(2) a = cosh(interval(-2, -1)) assert a.start == np.cosh(-1) assert a.end == np.cosh(-2) a = cosh(interval(-2, 1)) assert a.start == 1 assert a.end == np.cosh(-2) a = cosh(1) assert a.start == np.cosh(1) assert a.end == np.cosh(1)