A practical algorithm for calculating the eigenvalues of a symmetric matrix with real elements

This article presents a practical algorithm for calculating the eigenvalues of a symmetric matrix with real elements. Various computational methods for solving this problem have been analyzed and their disadvantages have been identified. An algorithm for calculating the eigenvalues of a matrix using standard built-in functions of Microsoft Excel or Libre-Office Calc is presented. Conclusions are drawn about the possibility of using the algorithm not only for symmetric matrices, but for simple matrices with real elements.