参数x服从beta分布，这里拟合beta分布惨回溯，在Update时出错了
model
{
   for(i in 1:N)
           {

              x[i]~dbeta(a,b)
           }
                      a~dunif(0,2)
                      b~dunif(0,2)
}
# Data
        list(N=54,x=c(0.239,0.111,0.865,0.481,0.1488,0.378,0.3,0.3595,0.3776,0.454,
0.36,0.2553,0.6126,0.796,0.454,1,0.343,0.426,0.631,0.556,0.426,0.372,0.387,0.248,0.372,0.2505,0.5367,0.3736,0.672,0.267,0.579,0.582,0.387,0.3396,0.7098,0.6288,0.6094,0.5816,0.5522,0.2068,
0.528,0.316,0.1189,0.357,0.4187,0.491,0.371,0.498,0.102,0.2068,0,0.283,0.641,0.387))
#initial data
        list(a=2,b=2);