t block column of an s.p.d. block Toeplitz
                  matrix was/is defined; if demanded, the Cholesky
                  factors R and L are lower and upper triangular,
                  respectively, and G contains the generator of the
                  inverse. This choice results in a column oriented
                  algorithm which is usually faster.
          Note:   in this routine, the notation x / y means that
                  x corresponds to TYPET = 'R' and y corresponds to
              