Is this simple symmetric matrix positive semi-definite?

48 Views Asked by At

Let the $n\times n$ symmetric matrix $A$, where $n\geq 9$ be given by \begin{equation} A_{i,j}= \begin{cases} 1.4, &\text{for } 1\leq i=j\leq 9\\ (0.9)^{|i-j|},&\text{for } 1\leq i\neq j\leq 9\\ 0, &\text{else } \end{cases} \end{equation} Is this matrix positive semi-definite? it look similar to the covariance matrix of the AR(1) process. So I guess yes.