> with(linalg):
Warning, the protected names norm and trace have been redefined and
unprotected

> lA:=matrix(4,4,[0,1,0,0, 0,0,l/EA,0, 0,theta*omega^2,0,1,  0,0,0,0]);

                      [0         1           0      0]
                      [                              ]
                      [                      l       ]
                      [0         0          ----    0]
                lA := [                      EA      ]
                      [                              ]
                      [                2             ]
                      [0    theta omega      0      1]
                      [                              ]
                      [0         0           0      0]

> delta:=matrix(4,4,[1,0,0,0,  0,1,0,0,  0,0,1,0,  0,0,0,1]);

                              [1    0    0    0]
                              [                ]
                              [0    1    0    0]
                     delta := [                ]
                              [0    0    1    0]
                              [                ]
                              [0    0    0    1]

> cp:=charpoly(lA,lambda);

                          2         2                 2
                    lambda  (-lambda  EA + theta omega  l)
            cp := - --------------------------------------
                                      EA

> solve(cp=0,lambda);

                           1/2                      1/2
               (EA theta l)    omega    (EA theta l)    omega
         0, 0, ---------------------, - ---------------------
                        EA                       EA

> 
> 
