Comments on "On a transformation of the-congruence Sylvester equation for the least squares optimization".

It is shown that the results obtained (using the Kronecker product) for solving the -congruence Sylvester equation [9] were previously obtained by the LMI method for solving the modified matrix Sylvester equation [1], and both equations coincide up to the notation of matrix coefficients. It is noted that the algorithm proposed in [1] is more general than the algorithms presented in [9]. Contrary to the results of [9], the simplicity of the algorithm [1] allows one to use the mincx.m MATLAB package procedure for solving the matrix Sylvester equations, the numerical solution of which gives the accuracy 10-11 and 10-15 respectively in two specific examples. [ABSTRACT FROM AUTHOR]