How can I find the axes of inertia of a 3D point cloud

I have 3 column vectors containing roughly 45k points for x, y, and z respectivley.

I have found the centroid but other than that I don't know where to begin.

Answer 1

[Sai Bhargav Avula]

Perform the Principal Component Analysis(PCA) on the point cloud. Each column of the coefficient matrix that the PCA returned correspond to one principal component. The coefficient column with the maximum score will give the axis which is the principal component of Inertia.  

For further details on MATLAB PCA check the link given below: 

https://www.mathworks.com/help/stats/pca.html