fix bug 128 : tridiagonalization failed for 1x1 matrices
fix bug 128 : tridiagonalization failed for 1x1 matrices

madlib/eigen_backup,rotorliu/eigen,rotorliu/eigen,rotorliu/eigen,mjbshaw/Eigen,mjbshaw/Eigen,mjbshaw/Eigen,madlib/eigen_backup,rotorliu/eigen,madlib/eigen_backup,mjbshaw/Eigen,madlib/eigen_backup