The most direct way to enter xI - B, where B is the matrix on page 103 is to use V = penter(2,4,[4 1;0 15; 0 -3; 4 -13]). Follow this with ldisp(V) to see that it is correct.
Another method is the following. First enter T = eye(2) to define T as the 2x2 identity matrix. Next, enter the matrix of numerators of B, call it BN = [-1 3;-15 13]. Then use V = penter(2,4,[4*T(:) -BN(:)]). (Note: there should be no space between the minus sign and BN.) Here T(:) calls for the column matrix whose entries are the columns of T taken one after the other and BN(:) is the column matrix whose entries are the columns of BN taken one after the other. Then [4*T(:) -BN(:)] is the matrix with two columns which is needed for `penter' in the case of this example.
Return to Chapter 9.