Each n-by-n matrix with n>1 is a sum of 5 coninvolutory matrices

Ma. Nerissa M. Abara, Dennis I. Merino, Vyacheslav I. Rabanovich +2

An $n\times n$ complex matrix $A$ is called coninvolutory if $\bar{A}A=I_n$ and skew-coninvolutory if $\bar{A}A=-I_n$ (which implies that $n$ is even). We prove that each matrix of s…