The Relationship Between Optimal Hankel Approximation and Truncation Approximation

This paper presented the relationship between two algorithms for approximating a given IIR filter by FIR filter, the optimal Hankel approximation algorithm and the direct truncation approximation algorithm. Firstly, we introduced the two algorithms in brief. Then, we proposed that the two algorithms equivalent under specific circumstances, and the conclusion was proved in theoretically in this paper. The correctness of the conclusion is demonstrated through five examples.