Simple rational approximation

The main application of SRA lies in finding the zeros of secular functions.

A divide-and-conquer algorithm to find the eigenvalues and eigenvectors for various kinds of matrices is well known in numerical analysis.

In a strict sense, SRA implies a specific interpolation using simple rational functions as a part of the divide-and-conquer algorithm.

The origin of the interpolation with rational functions can be found in the previous work done by Edmond Halley.

Similarly, we can derive a variation of Halley's formula based on a one-point second-order iterative method to solve

SRA strictly implies this one-point second-order interpolation by a simple rational function.