# modes_to_cg_ref¶

Returns the rigid body modes defined with respect to the centre of gravity

The transformation from the modes defined at the FoR A origin, $$\boldsymbol{\Phi}$$, to the modes defined using the centre of gravity as a reference is

$\boldsymbol{\Phi}_{rr,CG}|_{TRA} = \boldsymbol{\Phi}_{RR}|_{TRA} + \tilde{\mathbf{r}}_{CG} \boldsymbol{\Phi}_{RR}|_{ROT}$
$\boldsymbol{\Phi}_{rr,CG}|_{ROT} = \boldsymbol{\Phi}_{RR}|_{ROT}$
returns

Transformed eigenvectors

rtype

(np.array)