Solution of a Linear Nondegenerate Matrix Equation Based on the Zero Divisor

New formulas were obtained to solve the linear non-degenerate matrix equations based on zero divisors of numerical matrices. Two theorems were formulated, and a proof to one of them is provided. It is noted that the proof of the second theorem is similar to the proof of the first one. The proved theorem substantiates new formula in solving the equation equivalent in the sense of the solution uniqueness to the known formulas. Its fundamental difference lies in the following: any explicit matrix inversion or determinant calculation is missing; solution is "based" not on the left, but on the right side of the matrix equation; zero divisor method is used (it was never used in classical formulas for solving a matrix equation); zero divisor calculation is reduced to simple operations of permutating the vector elements on the right-hand side of the matrix equation. Examples are provided of applying the proposed method for solving a nondegenerate matrix equation to the numerical matrix equations. High accuracy of the proposed formulas for solving the matrix equations is demonstrated in comparison with standard solvers used in the MATLAB environment. Similar problems arise in the synthesis of fast and ultrafast iterative solvers of linear matrix equations, as well as in nonparametric identification of abnormal (emergency) modes in complex technical systems, for example, in the power systems

On the fraction of matrices with maximal additive complexity

The additive complexity of a nondegenerate matrix of size n is the minimum number of additions in a chain of elementary transformations over rows required to reduce the matrix to the identity one. It is shown that if the order of the field tends to infinity, then almost all matrices are of maximum possible additive complexity (n−1)n. The matrices of additive complexity (n − 1)n are shown to be MDS-matrices.