We can find a polynomial model of a time series in case its associated matrix is not diagonal and not of full rank by using the transformations of the exponential and the logarithm.

• 对于不能对角和不满秩的时间序列矩阵，运用指数对数的可逆变换及相关的列变换化为满秩可对角的时间序列矩阵，从而找到代数多项式模型。