public double p(int[] o, int[] s) {
        return Math.exp(logp(o, s));
    }
@Test
    public void testJointP() {
        System.out.println("joint p");
        int[] o = {0, 0, 1, 1, 0, 1, 1, 0};
        int[] s = {0, 0, 1, 1, 1, 1, 1, 0};
        HMM hmm = new HMM(pi, Matrix.of(a), Matrix.of(b));
        double expResult = 7.33836e-05;
        double result = hmm.p(o, s);
        assertEquals(expResult, result, 1E-10);
    }