On the closed form of the likelihood function of the first order moving average model
一阶移动平均模型似然函数的闭式表达
The covariance matrix of a first order moving average process is expressed as the product of the covariance matrix of the dual autoregressive process of order one and a near identity matrix. Its inverse is then obtained. The closed form of the likelihood function is derived. A comparison is made with some approximate likelihood functions.