Exception Handling in Tracking and Apertures

PTC and FPP have a collection of exception flags and settings to prevent undefined operations, exceeding apertures-- physical and/or mathematicals. Input settings

1. aperture_flag (=true) $\Longrightarrow$ Turns aperture checks on or off globally.
2. check_madx_aperture (=true) $\Longrightarrow$ Turns magnet aperture on globally if defined.
3. s_aperture_check (=true) $\Longrightarrow$ Turns INTEGRATION_NODE aperture on globally if defined for case0 node.
4. absolute_aperture (= 1) $\Longrightarrow$ Turns generic aperture on: prevents crashes and NAN.
5. hyperbolic_aperture (= 10) $\Longrightarrow$ Prevents various FPP defined functions with exponential arguments to crash.
6. no_hyperbolic_in_normal_form (=false) $\Longrightarrow$ If true, prevents a ``hyperbolic'' fixed point normal form, i.e., as in the case of an integer or half integer resonance.
7. real_warning (=true) $\Longrightarrow$ Detects single precision in FPP and returns an error.
8. da_absolute_aperture (= $10^6$) $\Longrightarrow$ Limits sizes while tracking with Berz's PPUSH algorithm.

Output information

1. check_stable (=true) $\Longrightarrow$ Detects single precision in FPP and returns an error.
2. stable_da (=true) $\Longrightarrow$ Detects a problem in Dabnew
3. messagelost (= Aperture has been reset ) $\Longrightarrow$ Default message which is changed when an exception is thrown.
4. lost_fibre nullified pointer to the FIBRE where the particle was lost.
5. lost_node nullified pointer to the INTEGRATION_NODE where the particle was lost.
6. xlost(1:6) zeros Contains the coordinates at the moment the particle gets lost at a PTC aperture.