Moments of Inertia: Finding the Eigenvalues of a Matrix

      \ensuremath{\gg} J = diag([1 3 5])
     
     J =
     
          1     0     0
          0     3     0
          0     0     5

      \ensuremath{\gg} ang1 = 30/180*pi
     
     ang1 =
     
         0.5236

      \ensuremath{\gg} Q1 = [1 0 0; 0 cos(ang1) sin(ang1) ; 0 -sin(ang1) cos(ang1)]
     
     Q1 =
     
         1.0000         0         0
              0    0.8660    0.5000
              0   -0.5000    0.8660
     
      \ensuremath{\gg} ang2 = 45/180*pi
     
     ang2 =
     
         0.7854
     
      \ensuremath{\gg} Q2 = [cos(ang2) sin(ang2) 0; -sin(ang2) cos(ang2) 0; 0 0 1]
     
     Q2 =
     
         0.7071    0.7071         0
        -0.7071    0.7071         0
              0         0    1.0000

      \ensuremath{\gg} Jrot = Q2*(Q1*J*Q1')*Q2'
     
     Jrot =
     
         2.2500    1.2500    0.6124
         1.2500    2.2500    0.6124
         0.6124    0.6124    4.5000

      \ensuremath{\gg} eig(Jrot)
     
     ans =
     
          1
          3
          5

previous    contents     next

Peter Junglas 8.3.2000