### Description

This example visualizes the analytical results of Boussinesq's problem from Saada. The figure shows the results by displaying the scaled and oriented principal axes of the stress tensor. (These are called *tensor axes*.)

!!! info
    See [Figure 6-22a](../../../VTKBook/06Chapter6/#Figure%206-22a) in [Chapter 6](../../../VTKBook/06Chapter6) the [VTK Textbook](../../../VTKBook/01Chapter1).
