You aren't supposed to "run" the manual like a script. You are supposed to inherit from classes ( G4VUserDetectorConstruction , G4VUserPhysicsList ). The manual is telling you which virtual functions to override.
The manual uses diagrams and pseudo-code to show how these objects interact inside the G4SteppingManager . Do not skip this chapter – it defines the mental model for everything that follows. geant4 manual
: Specify the particles and physical processes (electromagnetic, hadronic, etc.) to be simulated. You aren't supposed to "run" the manual like a script
For new users, the Geant4 Tutorial provided by MIT and introductory slides from Agenda INFN offer structured pathways to understanding the toolkit's modular kernel. Detailed walkthroughs are also available on Fermilab Conference Office and Oregon State University Open Source Lab . Physics Reference Manual - Geant4 The manual uses diagrams and pseudo-code to show
For over two decades, (GEometry ANd Tracking) has stood as the global standard toolkit for simulating the passage of particles through matter. Developed by a large international collaboration originally at CERN, it is the engine behind countless breakthroughs in high-energy physics, nuclear physics, medical physics, space exploration, and radiation shielding.
The manual is famous for giving you 90% of a code snippet, but not the main function. That is frustrating. However, those snippets are gold. If the manual shows a G4VUserPrimaryGeneratorAction , do not try to improvise. Type it exactly as shown, then slowly modify it.
These later chapters cover:
