OP Engine
Operator-partitioned ODE/PDE solver core with nine integration methods (explicit, IMEX, fully implicit), adaptive step-size control, and zero per-step allocation.
OP Engine (Operator-Partitioned Engine) is an operator-partitioned ODE/PDE solver core. It splits the right-hand side into an explicit nonlinear part and an optional stiff linear operator, then advances them jointly through a choice of nine integration methods:
- Explicit: Euler, Heun
- IMEX (implicit-explicit): Euler, Heun–trapezoidal, TR-BDF2
- Fully implicit: Euler, trapezoidal, BDF2, Rosenbrock-W2
Key design features:
- Adaptive step-size control with embedded error estimates
- Zero per-step allocation — all buffers pre-allocated at construction
- Cached implicit solves with dense/sparse autodispatch
- Stage operator factories for time- and state-dependent operators
Consumes model specifications and structured metadata from OP System and serves as the forward-simulation backend for campaign orchestrators like FlepiMoP2.