Question:
how can the initial values $\left(a[0],\,\dots,\,a[k-1]\right)$ and the coefficients $\left(c_k,\,\dots,\,c_0\right)$ be determined that solve
- $\min\limits_{a[0],\dots,a[k-1]\\ c_k,\dots,c_0} \left\|\left(x[0]-a[0],\,\dots,\,x[N]-a[N]\right)\right\|$
- $n\ge k\implies a[n]=c_0+\sum\limits_{i=1}^k c_ia[n-i]$
i.e. how to find for a given sequence the best approximating linear recursion with given depth $k$