Numerical algorithms for solving comrade linear systems based on tridiagonal solvers

Recently, two efficient algorithms for solving comrade linear systems have been proposed by Karawia [A.A. Karawia, Two algorithms for solving comrade linear systems, Appl. Math. Comput. 189 (2007) 291–297]. The two algorithms are based on the LU decomposition of the comrade matrix. In this paper, two algorithms are presented for solving the comrade linear systems based on the use of conventional fast tridiagonal solvers and an efficient way of evaluating the determinant of the comrade matrix is discussed.