- #1
bugatti79
- 794
- 1
I have an inertia tensor D in the old Cartesian system which i need to rotate through +90 in y and -90 in z to translate to the new system. I am using standard right hand rule notation for this Cartesian rotation.
[tex]D= \mathbf{\left(\begin{array}{lll}I_{xx}&I_{xy}&I_{xz}\\I_{yx}&I_{yy}&I_{yz}\\I_{zx}&I_{zy}&I_{zz}\\\end{array}\right)}[/tex], [tex]N_y(+90)=\mathbf{\left(\begin{array}{lll}0&0&1\\0&1&0\\-1&0&0\\\end{array}\right)}[/tex], [tex]N_z(-90)=\mathbf{\left(\begin{array}{lll}0&1&0\\-1&0&0\\0&0&1\\\end{array}\right)}[/tex]
If we let
[tex]N_R=N_z N_y[/tex] (I am pre-multiplying [tex]N_y[/tex] by [tex]N_z[/tex] because that is the order) and the transpose [tex]N'_R=N_R^T[/tex].
Is the the new system tensor [tex]N_RDN'_R[/tex] or [tex]N'_RDN_R[/tex]...?
[tex]D= \mathbf{\left(\begin{array}{lll}I_{xx}&I_{xy}&I_{xz}\\I_{yx}&I_{yy}&I_{yz}\\I_{zx}&I_{zy}&I_{zz}\\\end{array}\right)}[/tex], [tex]N_y(+90)=\mathbf{\left(\begin{array}{lll}0&0&1\\0&1&0\\-1&0&0\\\end{array}\right)}[/tex], [tex]N_z(-90)=\mathbf{\left(\begin{array}{lll}0&1&0\\-1&0&0\\0&0&1\\\end{array}\right)}[/tex]
If we let
[tex]N_R=N_z N_y[/tex] (I am pre-multiplying [tex]N_y[/tex] by [tex]N_z[/tex] because that is the order) and the transpose [tex]N'_R=N_R^T[/tex].
Is the the new system tensor [tex]N_RDN'_R[/tex] or [tex]N'_RDN_R[/tex]...?