23 Figure 1:c-pseudospectra (e=0.5,0.4,0.3,0.2,0.1)for the matrix A.The grid points are selected with v=80. 3 2 Figure 2:e-pseudospectra(e=0.5,0.4,0.3,0.2,0.1)for the matrix A(:,1:4).The grid points are selected with v=80. Example2 This test matrix is constructed by L.N.Trefethen(see[10]p255).Let A=AN=20 and grid points are selected with v=80,the numerical result is shown in Figure 3. 6−3 −2 −1 0 1 2 3 −3 −2 −1 0 1 2 3 fig.1 Figure 1:²−pseudospectra (² = 0.5, 0.4, 0.3, 0.2, 0.1) for the matrix A. The grid points are selected with v=80. −3 −2 −1 0 1 2 3 −3 −2 −1 0 1 2 3 fig.2 Figure 2:²−pseudospectra (² = 0.5, 0.4, 0.3, 0.2, 0.1) for the matrix A(:,1:4). The grid points are selected with v=80. Example2 This test matrix is constructed by L.N.Trefethen (see[10]p255). Let A = AN=20 and grid points are selected with v=80, the numerical result is shown in Figure 3. 6