ctplanet.InertiaTensor_from_C

ctplanet.InertiaTensor_from_C#

ctplanet.InertiaTensor_from_C(C, potential, normalize=False, r_norm=None, quiet=True)#

Calculate the inertia tensor given the polar moment of inertia and the gravitational potential coefficients.

Returns:

  • I (ndarray, size(3, 3)) – The inertia tensor.

  • A, B, C (float) – The principal moments of inertia, with A<B<C.

  • angles (ndarray, size(3,2)) – Matrix with each row containing the latitude and longitude coordinates (in degrees) of the principal moments A, B and C.

Parameters:

  • C (float) – The polar moment of inertia, which is assumed to be equal to the I33 component of the inertia tensor.

  • potential (SHGravCoeffs) – An SHGravCoeffs instance containing the gravitational potential coefficients.

  • normalize (bool, optional, default = False) – If True, return all moments normalized by MR^2

  • r_norm (float, optional, default = None) – If specified, and if normalize is True, use this radius to normalize all output moments of inertia. If normalize is False, then r_norm will be used when printing the normalized moments to screen when quiet is False.

  • quiet (bool, optional, default = True) – If False, print additional information, including the principal and normalized principal moments of inertial, and the directions of the axes of the principal moments.

Notes

This routine assumes that the polar moment of inertia C is equal to the I33 term of the inertia tensor. This is equivalent to assuming that the coordinate system defining the gravitational potential is aligned with the principal moment C. As such, the gravitational potential terms of order 2 and degree 1 should be identically zero. If they are not, the returned value of the largest principal moment will differ slightly from the input value, and the difference provides an estimate of the error associated with the assumption that C=I33.