This type is central to accelerator physics. Here I reproduce in jpeg form some transparencies from a PowerPoint presentation.
This presentation culminates with a program computing the dependence of a pendulum frequency with amplitude. This is obtained with the type NORMALFORM. The program is available here.
A Twiss function "do-loop" is displayed in the following PTC example: you must download a flat file of the ALS light source and a main program. Link it with FPP and PTC.