Simplify3D User Forum

I haven’t had a need to do math in Gcode but, I found this for Slic3r

https://manual.slic3r.org/advanced/conditional-gcode

Slic3r is a great App, especially if used in conjunction with Repeteir-Host (which, basically makes it a robust app similar to Simplify).

Perhaps the info can be a starting point for your Simplify scripts

"Terminal Commands for Post Processing" does not support {EVAL" "}. In {EVAL" "} called QJSEngine::evaluate::toNumber().
https://doc.qt.io/qt-5/qjsengine.html#evaluate
How to write a more advanced program in Javascript here, I can not imagine.