Technical Reference Overview

lob Technical Reference

lob computes the point-mass trajectory of a symmetric projectile: drag, gravity, wind, atmosphere, Coriolis, spin drift and aerodynamic jump. This site documents how it works — the physics, the numerics, the design choices and the evidence behind them. For a quick start, see Getting Started; for installation and packaging, see the repository README.md (intentionally separate from this reference).

How this documentation is organized

• Getting Started — Getting Started — build, install and minimal example. Start here if you have never built lob.
• API Reference
  • Builder — constructing a LobContext / lob::Context
  • Forward Solve — LobSolve() / lob::Solve()
  • Inverse Solve — LobSolveInverse() / LobFastInverse()
  • Context and Results — LobContext, LobOutput, lifetime
  • Errors — full LobErrorT catalog
  • Solver Options — StepSize / MaximumTime / MinimumSpeed/MinimumEnergy
  • Units — unit helpers and conversions
  • Physical Constants — physical constants (ISA, McCoy, Huang)
• Ballistic Model
  • Point-Mass Model — equations of motion
  • Drag Functions — standard curves, custom tables, splines
  • Atmospheric Model — ISA atmosphere, density, speed of sound
  • Wind and Coriolis — wind and Coriolis
  • Spin Drift and Aerodynamic Jump — spin drift and aerodynamic jump (Litz and Boatright)
• Numerical Methods
  • ODE Integration — Heun integration in down-range
  • Cubic Hermite Splines — cubic Hermite PCHIP splines
  • Zero-Angle Solver — zero-angle root finding
  • Inverse Solver — inverse (adjustment) solving and its shared solver
• Ballistic Coefficient
  • Ballistic Coefficient Overview — concepts
  • BC/Velocity-Band Transformation — BC/velocity-band transformation (math)
  • BC Bands Worked Example — figure and trajectory (worked example)
• Design Decisions
  • Design Decisions — why the library is shaped this way
  • Shared Angle Solver — the shared angle solver
• Validation
  • Validation — how correctness is established

Where to start

• New user → Getting Started then Builder.
• Auditing the physics → Point-Mass Model → Drag Functions → Atmospheric Model.
• Auditing the numerics → ODE Integration → Cubic Hermite Splines → Zero-Angle Solver.
• Understanding BC bands → BC Bands Worked Example (the most complete worked example).

Where to find the code

Implementation lives under source/; public headers under include/lob/:

• Builder and environment: LobBuilder, source/lob_builder.cpp
• Forward/inverse solves: LobSolve(), LobSolveInverse(), source/lob_solve.cpp
• Single step: source/solve_step.cpp, source/solve_step.hpp
• Angle solver: source/solve_angle.hpp
• Splines: source/splines.hpp
• Drag tables: source/tables.hpp
• Atmosphere/physics helpers: source/calc.hpp, source/constants.hpp
• Strong units: source/eng_units.hpp

Tests under test/source/ mirror each area and are cited from the technical pages as evidence rather than claims.