Octahedron_truncated_txtytz

This model provides the form factor, $P(q)$, for a general octahedron
with the possibility to be truncated differently along 3 directions (x,y,z).
This model is constructed in a similar way as the octahedron_truncated model. [1]
For example, it is suited to model a square bipyramid or square bifrustum.
3D visualisation of the shape is available using a Mathematica notebook. [2]

[1] calculation of the form factor is detailied here: https://sdrive.cnrs.fr/s/y6pfDRDZXAaW9yp
[2] https://www.wolframcloud.com/download/marianneimperor/Published/octa_txtytz
https://www.wolframcloud.com/obj/marianneimperor/Published/octa_txtytz_code.nb